diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 01e32d5c8..27e65c4da 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -115,8 +115,9 @@ jobs:
         run: go mod tidy && git diff --exit-code
       - name: Check natives build tags
         working-directory: ${{ env.GOPHERJS_PATH }}
-        # All those packages should have // +build js.
-        run: diff -u <(echo -n) <(go list ./compiler/natives/src/...)
+        run: |
+          echo "Any following packages have at least one file that is missing //go:build js"
+          diff -u <(echo -n) <(go list ./compiler/natives/src/...)
 
   go_tests:
     name: Go Tests
diff --git a/compiler/gopherjspkg/fs.go b/compiler/gopherjspkg/fs.go
index 0ec155308..caa07e11c 100644
--- a/compiler/gopherjspkg/fs.go
+++ b/compiler/gopherjspkg/fs.go
@@ -1,8 +1,6 @@
 package gopherjspkg
 
-import (
-	"net/http"
-)
+import "net/http"
 
 // FS is a virtual filesystem that contains core GopherJS packages.
 var FS http.FileSystem
diff --git a/compiler/natives/src/bufio/bufio_test.go b/compiler/natives/src/bufio/bufio_test.go
index b97fe22f7..f0ddf0534 100644
--- a/compiler/natives/src/bufio/bufio_test.go
+++ b/compiler/natives/src/bufio/bufio_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bufio_test
 
diff --git a/compiler/natives/src/bytes/bytes.go b/compiler/natives/src/bytes/bytes.go
index 1f74edc4f..15c014301 100644
--- a/compiler/natives/src/bytes/bytes.go
+++ b/compiler/natives/src/bytes/bytes.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bytes
 
diff --git a/compiler/natives/src/bytes/bytes_test.go b/compiler/natives/src/bytes/bytes_test.go
index e9d0e1690..5a2277f59 100644
--- a/compiler/natives/src/bytes/bytes_test.go
+++ b/compiler/natives/src/bytes/bytes_test.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package bytes_test
 
-import (
-	"testing"
-)
+import "testing"
 
 func dangerousSlice(t *testing.T) []byte {
 	t.Skip("dangerousSlice relies on syscall.Getpagesize, which GopherJS doesn't implement")
diff --git a/compiler/natives/src/compress/gzip/example_test.go b/compiler/natives/src/compress/gzip/example_test.go
index b3f6fbe43..37b3e734c 100644
--- a/compiler/natives/src/compress/gzip/example_test.go
+++ b/compiler/natives/src/compress/gzip/example_test.go
@@ -1,11 +1,8 @@
 //go:build js && wasm
-// +build js,wasm
 
 package gzip_test
 
-import (
-	"fmt"
-)
+import "fmt"
 
 // The test relies on a local HTTP server, which is not supported under NodeJS.
 func Example_compressingReader() {
diff --git a/compiler/natives/src/crypto/elliptic/nistec.go b/compiler/natives/src/crypto/elliptic/nistec.go
index 326c602d5..b2cc45e9d 100644
--- a/compiler/natives/src/crypto/elliptic/nistec.go
+++ b/compiler/natives/src/crypto/elliptic/nistec.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package elliptic
 
diff --git a/compiler/natives/src/crypto/internal/boring/bbig/big.go b/compiler/natives/src/crypto/internal/boring/bbig/big.go
index 3a726ba3c..170a6f983 100644
--- a/compiler/natives/src/crypto/internal/boring/bbig/big.go
+++ b/compiler/natives/src/crypto/internal/boring/bbig/big.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bbig
 
diff --git a/compiler/natives/src/crypto/internal/boring/bcache/cache.go b/compiler/natives/src/crypto/internal/boring/bcache/cache.go
index afff404ce..b33233211 100644
--- a/compiler/natives/src/crypto/internal/boring/bcache/cache.go
+++ b/compiler/natives/src/crypto/internal/boring/bcache/cache.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bcache
 
diff --git a/compiler/natives/src/crypto/internal/boring/bcache/cache_test.go b/compiler/natives/src/crypto/internal/boring/bcache/cache_test.go
index 12f2c4da4..9f50eb0ff 100644
--- a/compiler/natives/src/crypto/internal/boring/bcache/cache_test.go
+++ b/compiler/natives/src/crypto/internal/boring/bcache/cache_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bcache
 
diff --git a/compiler/natives/src/crypto/internal/boring/sig/sig.go b/compiler/natives/src/crypto/internal/boring/sig/sig.go
index 3eb2454aa..dab01104e 100644
--- a/compiler/natives/src/crypto/internal/boring/sig/sig.go
+++ b/compiler/natives/src/crypto/internal/boring/sig/sig.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sig
 
diff --git a/compiler/natives/src/crypto/internal/nistec/nistec_test.go b/compiler/natives/src/crypto/internal/nistec/nistec_test.go
index d755e7ec3..4da8ba9e3 100644
--- a/compiler/natives/src/crypto/internal/nistec/nistec_test.go
+++ b/compiler/natives/src/crypto/internal/nistec/nistec_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package nistec_test
 
diff --git a/compiler/natives/src/crypto/internal/nistec/wrapper.go b/compiler/natives/src/crypto/internal/nistec/wrapper.go
index 0d6706b52..a55aa4925 100644
--- a/compiler/natives/src/crypto/internal/nistec/wrapper.go
+++ b/compiler/natives/src/crypto/internal/nistec/wrapper.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package nistec
 
diff --git a/compiler/natives/src/crypto/internal/subtle/aliasing.go b/compiler/natives/src/crypto/internal/subtle/aliasing.go
index 145687d59..23c9843c8 100644
--- a/compiler/natives/src/crypto/internal/subtle/aliasing.go
+++ b/compiler/natives/src/crypto/internal/subtle/aliasing.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package subtle
 
diff --git a/compiler/natives/src/crypto/rand/rand.go b/compiler/natives/src/crypto/rand/rand.go
index 1c3631a02..4e4aab565 100644
--- a/compiler/natives/src/crypto/rand/rand.go
+++ b/compiler/natives/src/crypto/rand/rand.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package rand
 
diff --git a/compiler/natives/src/database/sql/driver/driver_test.go b/compiler/natives/src/database/sql/driver/driver_test.go
index 446da47c5..59ac867ef 100644
--- a/compiler/natives/src/database/sql/driver/driver_test.go
+++ b/compiler/natives/src/database/sql/driver/driver_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package driver
 
@@ -24,10 +23,10 @@ var valueConverterTests = []valueConverterTest{
 	{DefaultParameterConverter, (*int64)(nil), nil, ""},
 	{DefaultParameterConverter, &answer, answer, ""},
 	{DefaultParameterConverter, &now, now, ""},
-	//{DefaultParameterConverter, i(9), int64(9), ""}, // TODO: Fix.
+	//{DefaultParameterConverter, i(9), int64(9), ""}, // TODO: Fix. Errors with `driver.defaultConverter(driver.i(9)) = 9 (driver.i); want 9 (int64)`
 	{DefaultParameterConverter, f(0.1), float64(0.1), ""},
 	{DefaultParameterConverter, b(true), true, ""},
-	//{DefaultParameterConverter, bs{1}, []byte{1}, ""}, // TODO: Fix.
+	//{DefaultParameterConverter, bs{1}, []byte{1}, ""}, // TODO: Fix. Errors with `driver.defaultConverter(driver.bs([1])) = [1] (driver.bs); want [1] ([]uint8)`
 	{DefaultParameterConverter, s("a"), "a", ""},
 	{DefaultParameterConverter, is{1}, nil, "unsupported type driver.is, a slice of int"},
 }
diff --git a/compiler/natives/src/debug/pe/symbol.go b/compiler/natives/src/debug/pe/symbol.go
index 798502ce3..7564b8f77 100644
--- a/compiler/natives/src/debug/pe/symbol.go
+++ b/compiler/natives/src/debug/pe/symbol.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package pe
 
diff --git a/compiler/natives/src/embed/embed.go b/compiler/natives/src/embed/embed.go
index bb9738546..83cf729ac 100644
--- a/compiler/natives/src/embed/embed.go
+++ b/compiler/natives/src/embed/embed.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package embed
 
diff --git a/compiler/natives/src/encoding/gob/gob_test.go b/compiler/natives/src/encoding/gob/gob_test.go
index 823b572ac..32cd38bbd 100644
--- a/compiler/natives/src/encoding/gob/gob_test.go
+++ b/compiler/natives/src/encoding/gob/gob_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package gob
 
@@ -105,3 +104,7 @@ func TestTypeRace(t *testing.T) {
 	// cannot succeed when nosync is used.
 	t.Skip("using nosync")
 }
+
+func TestCountDecodeMallocs(t *testing.T) {
+	t.Skip("testing.AllocsPerRun not supported in GopherJS")
+}
diff --git a/compiler/natives/src/encoding/json/stream_test.go b/compiler/natives/src/encoding/json/stream_test.go
index adad8e153..484ee5c12 100644
--- a/compiler/natives/src/encoding/json/stream_test.go
+++ b/compiler/natives/src/encoding/json/stream_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package json
 
diff --git a/compiler/natives/src/fmt/fmt_test.go b/compiler/natives/src/fmt/fmt_test.go
index 70797693b..1a1c3278c 100644
--- a/compiler/natives/src/fmt/fmt_test.go
+++ b/compiler/natives/src/fmt/fmt_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package fmt_test
 
diff --git a/compiler/natives/src/go/parser/parser_test.go b/compiler/natives/src/go/parser/parser_test.go
index 7fded29fd..00f533233 100644
--- a/compiler/natives/src/go/parser/parser_test.go
+++ b/compiler/natives/src/go/parser/parser_test.go
@@ -2,9 +2,7 @@
 
 package parser
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestParseDepthLimit(t *testing.T) {
 	t.Skip("causes call stack exhaustion on js/ecmascript")
diff --git a/compiler/natives/src/go/token/position.go b/compiler/natives/src/go/token/position.go
index 6a1ee0c15..8cf111ab2 100644
--- a/compiler/natives/src/go/token/position.go
+++ b/compiler/natives/src/go/token/position.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package token
 
diff --git a/compiler/natives/src/go/token/token_test.go b/compiler/natives/src/go/token/token_test.go
index 335ee0776..9ef38348a 100644
--- a/compiler/natives/src/go/token/token_test.go
+++ b/compiler/natives/src/go/token/token_test.go
@@ -1,12 +1,9 @@
 //go:build js
-// +build js
 
 package token
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestFileSetRace(t *testing.T) {
-	t.Skip()
+	t.Skip("Fails with: WaitGroup counter not zero")
 }
diff --git a/compiler/natives/src/golang.org/x/crypto/internal/alias/alias.go b/compiler/natives/src/golang.org/x/crypto/internal/alias/alias.go
index a3e1e7f79..9b168a95a 100644
--- a/compiler/natives/src/golang.org/x/crypto/internal/alias/alias.go
+++ b/compiler/natives/src/golang.org/x/crypto/internal/alias/alias.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package alias
 
diff --git a/compiler/natives/src/golang.org/x/crypto/internal/subtle/aliasing.go b/compiler/natives/src/golang.org/x/crypto/internal/subtle/aliasing.go
index 145687d59..23c9843c8 100644
--- a/compiler/natives/src/golang.org/x/crypto/internal/subtle/aliasing.go
+++ b/compiler/natives/src/golang.org/x/crypto/internal/subtle/aliasing.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package subtle
 
diff --git a/compiler/natives/src/hash/maphash/maphash.go b/compiler/natives/src/hash/maphash/maphash.go
index 5c982404f..7c2a68cf6 100644
--- a/compiler/natives/src/hash/maphash/maphash.go
+++ b/compiler/natives/src/hash/maphash/maphash.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package maphash
 
-import (
-	_ "unsafe" // for linkname
-)
+import _ "unsafe" // for linkname
 
 // hashkey is similar how it is defined in runtime/alg.go for Go 1.19
 // to be used in hash{32,64}.go to seed the hash function as part of
diff --git a/compiler/natives/src/hash/maphash/maphash_test.go b/compiler/natives/src/hash/maphash/maphash_test.go
new file mode 100644
index 000000000..a1e9f45a9
--- /dev/null
+++ b/compiler/natives/src/hash/maphash/maphash_test.go
@@ -0,0 +1,53 @@
+//go:build js
+
+package maphash
+
+import "testing"
+
+//gopherjs:keep-original
+func TestSmhasherSmallKeys(t *testing.T) {
+	if !testing.Short() {
+		t.Skip("Causes a heap overflow in GopherJS when not --short")
+		// This test adds a lot of uint64 hashes into a map,
+		// (16,843,008 for long tests, 65,792 for short tests)
+		// inside `(s *hashSet) add(h uint64)` with `s.m[h] = struct{}{}`.
+		// This is to check the number of collisions in the hash function.
+	}
+	_gopherjs_original_TestSmhasherSmallKeys(t)
+}
+
+//gopherjs:keep-original
+func TestSmhasherZeros(t *testing.T) {
+	if !testing.Short() {
+		t.Skip("Too slow when not --short")
+		// This test creates a byte slice with 262,144 bytes for long tests
+		// and 1,024 for short tests filled by defualt with zeroes.
+		// Then it adds [:1], [:2], and so on upto the full slice.
+	}
+	_gopherjs_original_TestSmhasherZeros(t)
+}
+
+func TestSmhasherTwoNonzero(t *testing.T) {
+	// The original skips if `runtime.GOARCH == "wasm"` which means we should skip too.
+	t.Skip("Too slow on wasm and JS")
+}
+
+func TestSmhasherSparse(t *testing.T) {
+	// The original skips if `runtime.GOARCH == "wasm"` which means we should skip too.
+	t.Skip("Too slow on wasm and JS")
+}
+
+func TestSmhasherPermutation(t *testing.T) {
+	// The original skips if `runtime.GOARCH == "wasm"` which means we should skip too.
+	t.Skip("Too slow on wasm and JS")
+}
+
+func TestSmhasherAvalanche(t *testing.T) {
+	// The original skips if `runtime.GOARCH == "wasm"` which means we should skip too.
+	t.Skip("Too slow on wasm and JS")
+}
+
+func TestSmhasherWindowed(t *testing.T) {
+	// The original skips if `runtime.GOARCH == "wasm"` which means we should skip too.
+	t.Skip("Too slow on wasm and JS")
+}
diff --git a/compiler/natives/src/internal/bytealg/bytealg.go b/compiler/natives/src/internal/bytealg/bytealg.go
index dbcc6dec4..15a3c2d70 100644
--- a/compiler/natives/src/internal/bytealg/bytealg.go
+++ b/compiler/natives/src/internal/bytealg/bytealg.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bytealg
 
diff --git a/compiler/natives/src/internal/cpu/cpu.go b/compiler/natives/src/internal/cpu/cpu.go
index 794a58d6a..a8c25ea8e 100644
--- a/compiler/natives/src/internal/cpu/cpu.go
+++ b/compiler/natives/src/internal/cpu/cpu.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package cpu
 
diff --git a/compiler/natives/src/internal/fmtsort/fmtsort_test.go b/compiler/natives/src/internal/fmtsort/fmtsort_test.go
index f45987d72..50b65bb45 100644
--- a/compiler/natives/src/internal/fmtsort/fmtsort_test.go
+++ b/compiler/natives/src/internal/fmtsort/fmtsort_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package fmtsort_test
 
diff --git a/compiler/natives/src/internal/poll/semaphore.go b/compiler/natives/src/internal/poll/semaphore.go
index 5e4f5ea8d..112a37768 100644
--- a/compiler/natives/src/internal/poll/semaphore.go
+++ b/compiler/natives/src/internal/poll/semaphore.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package poll
 
-import (
-	_ "unsafe" // For go:linkname
-)
+import _ "unsafe" // For go:linkname
 
 //go:linkname runtime_Semacquire sync.runtime_Semacquire
 func runtime_Semacquire(s *uint32)
diff --git a/compiler/natives/src/internal/reflectlite/all_test.go b/compiler/natives/src/internal/reflectlite/all_test.go
index 4445189a0..66a7add0a 100644
--- a/compiler/natives/src/internal/reflectlite/all_test.go
+++ b/compiler/natives/src/internal/reflectlite/all_test.go
@@ -1,27 +1,7 @@
 //go:build js
-// +build js
 
 package reflectlite_test
 
-import (
-	"testing"
-
-	. "internal/reflectlite"
-)
-
-func TestTypes(t *testing.T) {
-	for i, tt := range typeTests {
-		if i == 30 {
-			continue
-		}
-		testReflectType(t, i, Field(ValueOf(tt.i), 0).Type(), tt.s)
-	}
-}
-
-func TestNameBytesAreAligned(t *testing.T) {
-	t.Skip("TestNameBytesAreAligned")
-}
-
 // `A` is used with `B[T any]` and is otherwise not needed.
 //
 //gopherjs:purge for go1.19 without generics
diff --git a/compiler/natives/src/internal/reflectlite/export_test.go b/compiler/natives/src/internal/reflectlite/export_test.go
index d663e65ba..c80ba65a8 100644
--- a/compiler/natives/src/internal/reflectlite/export_test.go
+++ b/compiler/natives/src/internal/reflectlite/export_test.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package reflectlite
 
-import (
-	"unsafe"
-)
+import "unsafe"
 
 // Field returns the i'th field of the struct v.
 // It panics if v's Kind is not Struct or i is out of range.
diff --git a/compiler/natives/src/internal/reflectlite/reflect_mirror_test.go b/compiler/natives/src/internal/reflectlite/reflect_mirror_test.go
deleted file mode 100644
index 01504f582..000000000
--- a/compiler/natives/src/internal/reflectlite/reflect_mirror_test.go
+++ /dev/null
@@ -1,12 +0,0 @@
-//go:build js
-// +build js
-
-package reflectlite_test
-
-import (
-	"testing"
-)
-
-func TestMirrorWithReflect(t *testing.T) {
-	t.Skip("TestMirrorWithReflect")
-}
diff --git a/compiler/natives/src/internal/reflectlite/reflectlite.go b/compiler/natives/src/internal/reflectlite/reflectlite.go
index d48f15987..f55eb4437 100644
--- a/compiler/natives/src/internal/reflectlite/reflectlite.go
+++ b/compiler/natives/src/internal/reflectlite/reflectlite.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflectlite
 
diff --git a/compiler/natives/src/internal/reflectlite/swapper.go b/compiler/natives/src/internal/reflectlite/swapper.go
index b8827c226..b324eb6e7 100644
--- a/compiler/natives/src/internal/reflectlite/swapper.go
+++ b/compiler/natives/src/internal/reflectlite/swapper.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflectlite
 
diff --git a/compiler/natives/src/internal/reflectlite/type.go b/compiler/natives/src/internal/reflectlite/type.go
index 0a41e862e..949599725 100644
--- a/compiler/natives/src/internal/reflectlite/type.go
+++ b/compiler/natives/src/internal/reflectlite/type.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflectlite
 
diff --git a/compiler/natives/src/internal/reflectlite/utils.go b/compiler/natives/src/internal/reflectlite/utils.go
index 1941f0d0e..c832bd4cf 100644
--- a/compiler/natives/src/internal/reflectlite/utils.go
+++ b/compiler/natives/src/internal/reflectlite/utils.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package reflectlite
 
-import (
-	"unsafe"
-)
+import "unsafe"
 
 type ChanDir int
 
diff --git a/compiler/natives/src/internal/reflectlite/value.go b/compiler/natives/src/internal/reflectlite/value.go
index 32d310723..12f8d292f 100644
--- a/compiler/natives/src/internal/reflectlite/value.go
+++ b/compiler/natives/src/internal/reflectlite/value.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflectlite
 
diff --git a/compiler/natives/src/internal/unsafeheader/unsafeheader_test.go b/compiler/natives/src/internal/unsafeheader/unsafeheader_test.go
index f20cf31fa..abe54639b 100644
--- a/compiler/natives/src/internal/unsafeheader/unsafeheader_test.go
+++ b/compiler/natives/src/internal/unsafeheader/unsafeheader_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package unsafeheader_test
 
diff --git a/compiler/natives/src/io/io_test.go b/compiler/natives/src/io/io_test.go
index d746b3709..36d70e3fa 100644
--- a/compiler/natives/src/io/io_test.go
+++ b/compiler/natives/src/io/io_test.go
@@ -1,14 +1,11 @@
 //go:build js
-// +build js
 
 package io_test
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestMultiWriter_WriteStringSingleAlloc(t *testing.T) {
-	t.Skip()
+	t.Skip("testing.AllocsPerRun not supported in GopherJS")
 }
 
 func TestMultiReaderFreesExhaustedReaders(t *testing.T) {
diff --git a/compiler/natives/src/math/big/big.go b/compiler/natives/src/math/big/big.go
deleted file mode 100644
index 25512db31..000000000
--- a/compiler/natives/src/math/big/big.go
+++ /dev/null
@@ -1,9 +0,0 @@
-//go:build js
-// +build js
-
-package big
-
-// TODO: This is a workaround for https://github.com/gopherjs/gopherjs/issues/652.
-//
-//	Remove after that issue is resolved.
-type Word uintptr
diff --git a/compiler/natives/src/math/big/big_test.go b/compiler/natives/src/math/big/big_test.go
index acad9a043..92989abe9 100644
--- a/compiler/natives/src/math/big/big_test.go
+++ b/compiler/natives/src/math/big/big_test.go
@@ -1,18 +1,9 @@
 //go:build js
-// +build js
 
 package big
 
 import "testing"
 
-func TestBytes(t *testing.T) {
-	t.Skip("broken")
-}
-
-func TestModSqrt(t *testing.T) {
-	t.Skip("slow")
-}
-
 func TestLinkerGC(t *testing.T) {
 	t.Skip("The test is specific to GC's linker.")
 }
diff --git a/compiler/natives/src/math/bits/bits.go b/compiler/natives/src/math/bits/bits.go
index b434603a4..cf4b66df6 100644
--- a/compiler/natives/src/math/bits/bits.go
+++ b/compiler/natives/src/math/bits/bits.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package bits
 
diff --git a/compiler/natives/src/math/math.go b/compiler/natives/src/math/math.go
index b0ed2da0d..fb0777b12 100644
--- a/compiler/natives/src/math/math.go
+++ b/compiler/natives/src/math/math.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package math
 
-import (
-	"github.com/gopherjs/gopherjs/js"
-)
+import "github.com/gopherjs/gopherjs/js"
 
 var (
 	math           = js.Global.Get("Math")
diff --git a/compiler/natives/src/math/math_test.go b/compiler/natives/src/math/math_test.go
deleted file mode 100644
index eb62dd1d1..000000000
--- a/compiler/natives/src/math/math_test.go
+++ /dev/null
@@ -1,22 +0,0 @@
-//go:build js
-// +build js
-
-package math_test
-
-import (
-	"testing"
-)
-
-// Slightly higher tolerances than upstream, otherwise TestGamma fails.
-// TODO: Is there a better way to fix TestGamma? It's weird that only one test
-//
-//	requires increasing tolerances. Perhaps there's a better fix? Maybe we
-//	should override TestGamma specifically and not the package-wide tolerances,
-//	because this will cause many other tests to be less accurate. Or maybe this
-//	is fine?
-func close(a, b float64) bool     { return tolerance(a, b, 4e-14) }
-func veryclose(a, b float64) bool { return tolerance(a, b, 6e-15) }
-
-func testExp(t *testing.T, Exp func(float64) float64, name string) {
-	t.Skip("inaccurate")
-}
diff --git a/compiler/natives/src/math/rand/rand_test.go b/compiler/natives/src/math/rand/rand_test.go
index 2246dfec4..0073850a0 100644
--- a/compiler/natives/src/math/rand/rand_test.go
+++ b/compiler/natives/src/math/rand/rand_test.go
@@ -1,14 +1,9 @@
 //go:build js
-// +build js
 
 package rand_test
 
 import "testing"
 
-func TestFloat32(t *testing.T) {
-	t.Skip("slow")
-}
-
 func TestConcurrent(t *testing.T) {
 	t.Skip("using nosync")
 }
diff --git a/compiler/natives/src/net/fastrand.go b/compiler/natives/src/net/fastrand.go
index 8feafc78f..878f970a5 100644
--- a/compiler/natives/src/net/fastrand.go
+++ b/compiler/natives/src/net/fastrand.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package net
 
-import (
-	_ "unsafe" // For go:linkname
-)
+import _ "unsafe" // For go:linkname
 
 //go:linkname fastrandu runtime.fastrandu
 func fastrandu() uint
diff --git a/compiler/natives/src/net/http/client_test.go b/compiler/natives/src/net/http/client_test.go
index 302b800df..f8c3b744e 100644
--- a/compiler/natives/src/net/http/client_test.go
+++ b/compiler/natives/src/net/http/client_test.go
@@ -2,9 +2,7 @@
 
 package http_test
 
-import (
-	"testing"
-)
+import "testing"
 
 func testClientTimeout(t *testing.T, h2 bool) {
 	// The original test expects Client.Timeout error to be returned, but under
diff --git a/compiler/natives/src/net/http/clientserver_test.go b/compiler/natives/src/net/http/clientserver_test.go
index 35b44dd4d..a95a5a0ca 100644
--- a/compiler/natives/src/net/http/clientserver_test.go
+++ b/compiler/natives/src/net/http/clientserver_test.go
@@ -1,16 +1,14 @@
 //go:build js && wasm
-// +build js,wasm
 
 package http_test
 
-import (
-	"testing"
-)
+import "testing"
 
 func testTransportGCRequest(t *testing.T, h2, body bool) {
 	t.Skip("The test relies on runtime.SetFinalizer(), which is not supported by GopherJS.")
 }
 
 func testWriteHeaderAfterWrite(t *testing.T, h2, hijack bool) {
+	// See: https://github.com/gopherjs/gopherjs/issues/1085
 	t.Skip("GopherJS source maps don't preserve original function names in stack traces, which this test relied on.")
 }
diff --git a/compiler/natives/src/net/http/cookiejar/example_test.go b/compiler/natives/src/net/http/cookiejar/example_test.go
index 09de5d0cf..7171867c1 100644
--- a/compiler/natives/src/net/http/cookiejar/example_test.go
+++ b/compiler/natives/src/net/http/cookiejar/example_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package cookiejar_test
 
diff --git a/compiler/natives/src/net/http/http.go b/compiler/natives/src/net/http/http.go
index 8fd607c4d..fbd7a8927 100644
--- a/compiler/natives/src/net/http/http.go
+++ b/compiler/natives/src/net/http/http.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package http
 
diff --git a/compiler/natives/src/net/http/http_wasm_test.go b/compiler/natives/src/net/http/http_wasm_test.go
index d078c0ea3..4c10efd9a 100644
--- a/compiler/natives/src/net/http/http_wasm_test.go
+++ b/compiler/natives/src/net/http/http_wasm_test.go
@@ -1,5 +1,4 @@
 //go:build js && wasm
-// +build js,wasm
 
 package http
 
diff --git a/compiler/natives/src/net/http/main_test.go b/compiler/natives/src/net/http/main_test.go
index bb747d123..2b2e3ec32 100644
--- a/compiler/natives/src/net/http/main_test.go
+++ b/compiler/natives/src/net/http/main_test.go
@@ -1,5 +1,4 @@
 //go:build js && wasm
-// +build js,wasm
 
 package http_test
 
diff --git a/compiler/natives/src/net/http/server_test.go b/compiler/natives/src/net/http/server_test.go
index f55704dcf..7223713d9 100644
--- a/compiler/natives/src/net/http/server_test.go
+++ b/compiler/natives/src/net/http/server_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package http_test
 
@@ -8,3 +7,8 @@ import "testing"
 func TestTimeoutHandlerSuperfluousLogs(t *testing.T) {
 	t.Skip("https://github.com/gopherjs/gopherjs/issues/1085")
 }
+
+func TestHTTP2WriteDeadlineExtendedOnNewRequest(t *testing.T) {
+	// Test depends on httptest.NewUnstartedServer
+	t.Skip("Network access not supported by GopherJS.")
+}
diff --git a/compiler/natives/src/net/http/transport_test.go b/compiler/natives/src/net/http/transport_test.go
index a173e47e7..2ece96853 100644
--- a/compiler/natives/src/net/http/transport_test.go
+++ b/compiler/natives/src/net/http/transport_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package http_test
 
diff --git a/compiler/natives/src/net/netip/export_test.go b/compiler/natives/src/net/netip/export_test.go
index 03b7cbe1b..fca2dc07c 100644
--- a/compiler/natives/src/net/netip/export_test.go
+++ b/compiler/natives/src/net/netip/export_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package netip
 
diff --git a/compiler/natives/src/net/netip/fuzz_test.go b/compiler/natives/src/net/netip/fuzz_test.go
index f7359c5bb..574201d2d 100644
--- a/compiler/natives/src/net/netip/fuzz_test.go
+++ b/compiler/natives/src/net/netip/fuzz_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package netip_test
 
diff --git a/compiler/natives/src/net/netip/netip.go b/compiler/natives/src/net/netip/netip.go
index 9d2b8b2d6..61b40fc24 100644
--- a/compiler/natives/src/net/netip/netip.go
+++ b/compiler/natives/src/net/netip/netip.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package netip
 
diff --git a/compiler/natives/src/net/netip/netip_test.go b/compiler/natives/src/net/netip/netip_test.go
index 46b116c00..280929425 100644
--- a/compiler/natives/src/net/netip/netip_test.go
+++ b/compiler/natives/src/net/netip/netip_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package netip_test
 
diff --git a/compiler/natives/src/os/file.go b/compiler/natives/src/os/file.go
index a3683b8b0..2df42121a 100644
--- a/compiler/natives/src/os/file.go
+++ b/compiler/natives/src/os/file.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package os
 
diff --git a/compiler/natives/src/os/os.go b/compiler/natives/src/os/os.go
index a45e13508..103ccb288 100644
--- a/compiler/natives/src/os/os.go
+++ b/compiler/natives/src/os/os.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package os
 
diff --git a/compiler/natives/src/os/signal/signal.go b/compiler/natives/src/os/signal/signal.go
index fe38d22b2..b39453926 100644
--- a/compiler/natives/src/os/signal/signal.go
+++ b/compiler/natives/src/os/signal/signal.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package signal
 
diff --git a/compiler/natives/src/reflect/example_test.go b/compiler/natives/src/reflect/example_test.go
index 0deab2ed5..65abf3dd6 100644
--- a/compiler/natives/src/reflect/example_test.go
+++ b/compiler/natives/src/reflect/example_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflect_test
 
diff --git a/compiler/natives/src/reflect/reflect.go b/compiler/natives/src/reflect/reflect.go
index 81f4c7b08..f1f24e559 100644
--- a/compiler/natives/src/reflect/reflect.go
+++ b/compiler/natives/src/reflect/reflect.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflect
 
diff --git a/compiler/natives/src/reflect/reflect_test.go b/compiler/natives/src/reflect/reflect_test.go
index 4c0bcd0be..9fb413c65 100644
--- a/compiler/natives/src/reflect/reflect_test.go
+++ b/compiler/natives/src/reflect/reflect_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflect_test
 
diff --git a/compiler/natives/src/reflect/swapper.go b/compiler/natives/src/reflect/swapper.go
index 068f984ed..d951ff668 100644
--- a/compiler/natives/src/reflect/swapper.go
+++ b/compiler/natives/src/reflect/swapper.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package reflect
 
diff --git a/compiler/natives/src/regexp/regexp_test.go b/compiler/natives/src/regexp/regexp_test.go
index 3a2d58d32..471281fa1 100644
--- a/compiler/natives/src/regexp/regexp_test.go
+++ b/compiler/natives/src/regexp/regexp_test.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package regexp
 
-import (
-	"testing"
-)
+import "testing"
 
 //gopherjs:keep-original
 func TestOnePassCutoff(t *testing.T) {
diff --git a/compiler/natives/src/runtime/debug/debug.go b/compiler/natives/src/runtime/debug/debug.go
index b45da62bb..ed9c0e34f 100644
--- a/compiler/natives/src/runtime/debug/debug.go
+++ b/compiler/natives/src/runtime/debug/debug.go
@@ -1,8 +1,9 @@
 //go:build js
-// +build js
 
 package debug
 
+import "time"
+
 func setGCPercent(int32) int32 {
 	// Not implemented. Return initial setting.
 	return 100
@@ -13,3 +14,26 @@ func setMaxStack(bytes int) int {
 	// The initial setting is 1 GB on 64-bit systems, 250 MB on 32-bit systems.
 	return 250000000
 }
+
+func readGCStats(pauses *[]time.Duration) {
+	// Not implemented. No GC stats available in this environment.
+}
+
+func freeOSMemory() {
+	// Not implemented. No OS memory management in this environment.
+}
+
+func setPanicOnFault(bool) bool {
+	// Not implemented.
+	return true
+}
+
+func setMaxThreads(int) int {
+	// Not implemented.
+	return 10000
+}
+
+func setMemoryLimit(int64) int64 {
+	// Not implemented.
+	return 0
+}
diff --git a/compiler/natives/src/runtime/debug/debug_test.go b/compiler/natives/src/runtime/debug/debug_test.go
new file mode 100644
index 000000000..7c7bf855f
--- /dev/null
+++ b/compiler/natives/src/runtime/debug/debug_test.go
@@ -0,0 +1,13 @@
+//go:build js
+
+package debug_test
+
+import "testing"
+
+func TestReadGCStats(t *testing.T) {
+	t.Skip(`This test uses runtime.GC(), which GopherJS doesn't support`)
+}
+
+func TestFreeOSMemory(t *testing.T) {
+	t.Skip(`This test uses runtime.GC(), which GopherJS doesn't support`)
+}
diff --git a/compiler/natives/src/runtime/fastrand.go b/compiler/natives/src/runtime/fastrand.go
index a5f2bdbb8..b902a5177 100644
--- a/compiler/natives/src/runtime/fastrand.go
+++ b/compiler/natives/src/runtime/fastrand.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package runtime
 
diff --git a/compiler/natives/src/runtime/pprof/pprof.go b/compiler/natives/src/runtime/pprof/pprof.go
index f398ca21b..512ef1a5b 100644
--- a/compiler/natives/src/runtime/pprof/pprof.go
+++ b/compiler/natives/src/runtime/pprof/pprof.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package pprof
 
diff --git a/compiler/natives/src/runtime/runtime.go b/compiler/natives/src/runtime/runtime.go
index 9f8425af8..56846b018 100644
--- a/compiler/natives/src/runtime/runtime.go
+++ b/compiler/natives/src/runtime/runtime.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package runtime
 
-import (
-	"github.com/gopherjs/gopherjs/js"
-)
+import "github.com/gopherjs/gopherjs/js"
 
 const (
 	GOOS     = "js"
diff --git a/compiler/natives/src/strconv/atoi.go b/compiler/natives/src/strconv/atoi.go
index 63ea9b732..1f26293a3 100644
--- a/compiler/natives/src/strconv/atoi.go
+++ b/compiler/natives/src/strconv/atoi.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package strconv
 
-import (
-	"github.com/gopherjs/gopherjs/js"
-)
+import "github.com/gopherjs/gopherjs/js"
 
 const (
 	maxInt32 float64 = 1<<31 - 1
diff --git a/compiler/natives/src/strconv/itoa.go b/compiler/natives/src/strconv/itoa.go
index c5440c78e..04dac0b71 100644
--- a/compiler/natives/src/strconv/itoa.go
+++ b/compiler/natives/src/strconv/itoa.go
@@ -1,11 +1,8 @@
 //go:build js
-// +build js
 
 package strconv
 
-import (
-	"github.com/gopherjs/gopherjs/js"
-)
+import "github.com/gopherjs/gopherjs/js"
 
 // Itoa in gopherjs is always a 32bit int so the native toString
 // always handles it successfully.
diff --git a/compiler/natives/src/strings/strings.go b/compiler/natives/src/strings/strings.go
index 2867872f6..6d8bedd54 100644
--- a/compiler/natives/src/strings/strings.go
+++ b/compiler/natives/src/strings/strings.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package strings
 
diff --git a/compiler/natives/src/strings/strings_test.go b/compiler/natives/src/strings/strings_test.go
index fb9a4a57a..adc05d6c5 100644
--- a/compiler/natives/src/strings/strings_test.go
+++ b/compiler/natives/src/strings/strings_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package strings_test
 
diff --git a/compiler/natives/src/sync/atomic/atomic.go b/compiler/natives/src/sync/atomic/atomic.go
index 1cbfe65f9..99aa8559f 100644
--- a/compiler/natives/src/sync/atomic/atomic.go
+++ b/compiler/natives/src/sync/atomic/atomic.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package atomic
 
diff --git a/compiler/natives/src/sync/atomic/atomic_test.go b/compiler/natives/src/sync/atomic/atomic_test.go
index e1ec6086c..8dbd0d027 100644
--- a/compiler/natives/src/sync/atomic/atomic_test.go
+++ b/compiler/natives/src/sync/atomic/atomic_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package atomic_test
 
diff --git a/compiler/natives/src/sync/cond.go b/compiler/natives/src/sync/cond.go
index 916ace8f7..1f94d5284 100644
--- a/compiler/natives/src/sync/cond.go
+++ b/compiler/natives/src/sync/cond.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync
 
diff --git a/compiler/natives/src/sync/cond_test.go b/compiler/natives/src/sync/cond_test.go
index 3b286ba49..e530b9625 100644
--- a/compiler/natives/src/sync/cond_test.go
+++ b/compiler/natives/src/sync/cond_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync_test
 
diff --git a/compiler/natives/src/sync/map_test.go b/compiler/natives/src/sync/map_test.go
index 432096071..5e8460411 100644
--- a/compiler/natives/src/sync/map_test.go
+++ b/compiler/natives/src/sync/map_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync_test
 
diff --git a/compiler/natives/src/sync/pool.go b/compiler/natives/src/sync/pool.go
index 9d3825e14..c865ca5dc 100644
--- a/compiler/natives/src/sync/pool.go
+++ b/compiler/natives/src/sync/pool.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync
 
diff --git a/compiler/natives/src/sync/pool_test.go b/compiler/natives/src/sync/pool_test.go
index ea35fd136..09ab79b32 100644
--- a/compiler/natives/src/sync/pool_test.go
+++ b/compiler/natives/src/sync/pool_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync_test
 
diff --git a/compiler/natives/src/sync/sync.go b/compiler/natives/src/sync/sync.go
index 294b0b109..5ca82694e 100644
--- a/compiler/natives/src/sync/sync.go
+++ b/compiler/natives/src/sync/sync.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync
 
diff --git a/compiler/natives/src/sync/waitgroup.go b/compiler/natives/src/sync/waitgroup.go
index e1f20eeb6..99cb49ff7 100644
--- a/compiler/natives/src/sync/waitgroup.go
+++ b/compiler/natives/src/sync/waitgroup.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package sync
 
diff --git a/compiler/natives/src/syscall/fs_js.go b/compiler/natives/src/syscall/fs_js.go
index 5a0a5a64d..23c2b2145 100644
--- a/compiler/natives/src/syscall/fs_js.go
+++ b/compiler/natives/src/syscall/fs_js.go
@@ -2,9 +2,7 @@
 
 package syscall
 
-import (
-	"syscall/js"
-)
+import "syscall/js"
 
 // fsCall emulates a file system-related syscall via a corresponding NodeJS fs
 // API.
diff --git a/compiler/natives/src/syscall/js/export_test.go b/compiler/natives/src/syscall/js/export_test.go
index 8f030c4d7..fb133a150 100644
--- a/compiler/natives/src/syscall/js/export_test.go
+++ b/compiler/natives/src/syscall/js/export_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package js
 
diff --git a/compiler/natives/src/syscall/js/js.go b/compiler/natives/src/syscall/js/js.go
index c0c18a614..03a09fde8 100644
--- a/compiler/natives/src/syscall/js/js.go
+++ b/compiler/natives/src/syscall/js/js.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package js
 
diff --git a/compiler/natives/src/syscall/js/js_test.go b/compiler/natives/src/syscall/js/js_test.go
index 999266da2..4c6e091df 100644
--- a/compiler/natives/src/syscall/js/js_test.go
+++ b/compiler/natives/src/syscall/js/js_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package js_test
 
diff --git a/compiler/natives/src/syscall/legacy.go b/compiler/natives/src/syscall/legacy.go
index beb99eb78..ad1df8bda 100644
--- a/compiler/natives/src/syscall/legacy.go
+++ b/compiler/natives/src/syscall/legacy.go
@@ -2,9 +2,7 @@
 
 package syscall
 
-import (
-	"github.com/gopherjs/gopherjs/js"
-)
+import "github.com/gopherjs/gopherjs/js"
 
 var (
 	syscallModule      *js.Object
diff --git a/compiler/natives/src/syscall/syscall_js_wasm.go b/compiler/natives/src/syscall/syscall_js_wasm.go
index 5bcbdeed4..648c228cb 100644
--- a/compiler/natives/src/syscall/syscall_js_wasm.go
+++ b/compiler/natives/src/syscall/syscall_js_wasm.go
@@ -1,8 +1,6 @@
 package syscall
 
-import (
-	"syscall/js"
-)
+import "syscall/js"
 
 func runtime_envs() []string {
 	process := js.Global().Get("process")
diff --git a/compiler/natives/src/testing/allocs_test.go b/compiler/natives/src/testing/allocs_test.go
index 54c2f545b..e1f4cffba 100644
--- a/compiler/natives/src/testing/allocs_test.go
+++ b/compiler/natives/src/testing/allocs_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package testing_test
 
diff --git a/compiler/natives/src/testing/example.go b/compiler/natives/src/testing/example.go
index bf8d06482..8568fec2c 100644
--- a/compiler/natives/src/testing/example.go
+++ b/compiler/natives/src/testing/example.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package testing
 
diff --git a/compiler/natives/src/testing/helper_test.go b/compiler/natives/src/testing/helper_test.go
index 6815fd651..3615da315 100644
--- a/compiler/natives/src/testing/helper_test.go
+++ b/compiler/natives/src/testing/helper_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package testing
 
diff --git a/compiler/natives/src/testing/helperfuncs_test.go b/compiler/natives/src/testing/helperfuncs_test.go
index 54a1ee737..560c0466a 100644
--- a/compiler/natives/src/testing/helperfuncs_test.go
+++ b/compiler/natives/src/testing/helperfuncs_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package testing
 
diff --git a/compiler/natives/src/testing/quick/quick.go b/compiler/natives/src/testing/quick/quick.go
index 51fa843aa..bd9bccf3e 100644
--- a/compiler/natives/src/testing/quick/quick.go
+++ b/compiler/natives/src/testing/quick/quick.go
@@ -13,12 +13,11 @@ var maxCountCap int = 0
 // reasonable amount of time. This is a better compromise than disabling a slow
 // test entirely.
 //
-//     //gopherjs:keep-original
-//     func TestFoo(t *testing.T) {
-//         t.Cleanup(quick.GopherJSInternalMaxCountCap(100))
-//         _gopherjs_original_TestFoo(t)
-//     }
-
+//	//gopherjs:keep-original
+//	func TestFoo(t *testing.T) {
+//	    t.Cleanup(quick.GopherJSInternalMaxCountCap(100))
+//	    _gopherjs_original_TestFoo(t)
+//	}
 func GopherJSInternalMaxCountCap(newCap int) (restore func()) {
 	previousCap := maxCountCap
 	maxCountCap = newCap
diff --git a/compiler/natives/src/testing/sub_test.go b/compiler/natives/src/testing/sub_test.go
index 1e9a79e47..300045db3 100644
--- a/compiler/natives/src/testing/sub_test.go
+++ b/compiler/natives/src/testing/sub_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package testing
 
diff --git a/compiler/natives/src/text/template/template.go b/compiler/natives/src/text/template/template.go
index 056fe9c85..d5cf5de56 100644
--- a/compiler/natives/src/text/template/template.go
+++ b/compiler/natives/src/text/template/template.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package template
 
diff --git a/compiler/natives/src/time/time.go b/compiler/natives/src/time/time.go
index 40c596e68..3b0cb0ef4 100644
--- a/compiler/natives/src/time/time.go
+++ b/compiler/natives/src/time/time.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package time
 
diff --git a/compiler/natives/src/time/time_test.go b/compiler/natives/src/time/time_test.go
index 5d4119cc6..777fe11fe 100644
--- a/compiler/natives/src/time/time_test.go
+++ b/compiler/natives/src/time/time_test.go
@@ -1,16 +1,13 @@
 //go:build js
-// +build js
 
 package time_test
 
-import (
-	"testing"
-)
+import "testing"
 
-func TestSleep(t *testing.T) {
-	t.Skip("time.Now() is not accurate enough for the test")
+func TestZeroTimer(t *testing.T) {
+	t.Skip(`This test is very slow (about 19 mins)`)
 }
 
-func TestEnvTZUsage(t *testing.T) {
-	t.Skip("TZ environment variable in not applicable in the browser context.")
+func TestSleep(t *testing.T) {
+	t.Skip("time.Now() is not accurate enough for the test")
 }
diff --git a/compiler/natives/src/time/zoneinfo_js.go b/compiler/natives/src/time/zoneinfo_js.go
index 0101b95f9..2932b9cf0 100644
--- a/compiler/natives/src/time/zoneinfo_js.go
+++ b/compiler/natives/src/time/zoneinfo_js.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package time
 
diff --git a/compiler/natives/src/time/zoneinfo_unix_test.go b/compiler/natives/src/time/zoneinfo_unix_test.go
new file mode 100644
index 000000000..8cb20416e
--- /dev/null
+++ b/compiler/natives/src/time/zoneinfo_unix_test.go
@@ -0,0 +1,9 @@
+//go:build js && unix && !ios && !android
+
+package time_test
+
+import "testing"
+
+func TestEnvTZUsage(t *testing.T) {
+	t.Skip("TZ environment variable in not applicable in the browser context.")
+}
diff --git a/compiler/natives/src/unicode/unicode.go b/compiler/natives/src/unicode/unicode.go
index a622c32f1..806f72bdb 100644
--- a/compiler/natives/src/unicode/unicode.go
+++ b/compiler/natives/src/unicode/unicode.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package unicode
 
diff --git a/compiler/natives/src/vendor/golang.org/x/crypto/internal/subtle/aliasing.go b/compiler/natives/src/vendor/golang.org/x/crypto/internal/subtle/aliasing.go
index 104ac82bb..0b515aeee 100644
--- a/compiler/natives/src/vendor/golang.org/x/crypto/internal/subtle/aliasing.go
+++ b/compiler/natives/src/vendor/golang.org/x/crypto/internal/subtle/aliasing.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package subtle
 
diff --git a/internal/sysutil/sysutil.go b/internal/sysutil/sysutil.go
index e19eb02e1..8fc72403d 100644
--- a/internal/sysutil/sysutil.go
+++ b/internal/sysutil/sysutil.go
@@ -1,5 +1,4 @@
 //go:build !windows
-// +build !windows
 
 // Package sysutil contains system-specific utilities.
 package sysutil
diff --git a/js/js_test.go b/js/js_test.go
index d7a904954..53fee6473 100644
--- a/js/js_test.go
+++ b/js/js_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package js_test
 
diff --git a/tests/alias_test.go b/tests/alias_test.go
index 9e791856e..ecd911d9d 100644
--- a/tests/alias_test.go
+++ b/tests/alias_test.go
@@ -1,8 +1,6 @@
 package tests
 
-import (
-	"testing"
-)
+import "testing"
 
 type foo struct {
 	a int
diff --git a/tests/compiler_test.go b/tests/compiler_test.go
index 7c72e3535..e33d24efe 100644
--- a/tests/compiler_test.go
+++ b/tests/compiler_test.go
@@ -1,8 +1,6 @@
 package tests
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestVariadicNil(t *testing.T) {
 	t.Run("only variadic", func(t *testing.T) {
diff --git a/tests/gorepo/run.go b/tests/gorepo/run.go
index 3685e99d6..0cb3b8143 100644
--- a/tests/gorepo/run.go
+++ b/tests/gorepo/run.go
@@ -1,5 +1,4 @@
 //go:build ignore
-// +build ignore
 
 // skip
 
diff --git a/tests/js_test.go b/tests/js_test.go
index 6f6eaa542..bed64179c 100644
--- a/tests/js_test.go
+++ b/tests/js_test.go
@@ -1,5 +1,4 @@
 //go:build js && !wasm
-// +build js,!wasm
 
 package tests_test
 
diff --git a/tests/map_js_test.go b/tests/map_js_test.go
index c815661ab..04847d3d4 100644
--- a/tests/map_js_test.go
+++ b/tests/map_js_test.go
@@ -1,5 +1,4 @@
 //go:build js && !wasm
-// +build js,!wasm
 
 package tests
 
diff --git a/tests/syscall_test.go b/tests/syscall_test.go
index 104800df7..ea880a218 100644
--- a/tests/syscall_test.go
+++ b/tests/syscall_test.go
@@ -1,5 +1,4 @@
 //go:build js
-// +build js
 
 package tests
 
diff --git a/tests/testdata/legacy_syscall/main.go b/tests/testdata/legacy_syscall/main.go
index 75ba22f6b..359d737af 100644
--- a/tests/testdata/legacy_syscall/main.go
+++ b/tests/testdata/legacy_syscall/main.go
@@ -1,5 +1,4 @@
 //go:build legacy_syscall && gopherjs
-// +build legacy_syscall,gopherjs
 
 // This program tests GopherJS's ability to perform raw syscalls using the
 // deprecated node_syscall extension. See TestLegacySyscall.