diff --git a/.github/workflows/master.yml b/.github/workflows/master.yml
index ad3f9f2..ad30fb2 100644
--- a/.github/workflows/master.yml
+++ b/.github/workflows/master.yml
@@ -15,13 +15,13 @@ jobs:
       MAVEN_CENTRAL_PGP_KEY: ${{ secrets.MAVEN_CENTRAL_PGP_KEY }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: gradle/actions/wrapper-validation@v4
-      - name: Set up JDK 11
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '11'
-          distribution: 'temurin'
+          java-version: '21'
+          distribution: 'corretto'
           check-latest: true
       # Configure Gradle for optimal use in GiHub Actions, including caching of downloaded dependencies.
       # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md
diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 573e169..4900736 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -13,13 +13,13 @@ jobs:
   buildAndTest:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: gradle/actions/wrapper-validation@v4
-      - name: Set up JDK 11
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '11'
-          distribution: 'temurin'
+          java-version: '21'
+          distribution: 'corretto'
           check-latest: true
       # Configure Gradle for optimal use in GiHub Actions, including caching of downloaded dependencies.
       # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 64ef19c..de556bb 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -19,13 +19,13 @@ jobs:
       RELEASE_VERSION: ${{ github.event.inputs.version }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - uses: gradle/actions/wrapper-validation@v4
-      - name: Set up JDK 11
+      - name: Set up JDK 21
         uses: actions/setup-java@v4
         with:
-          java-version: '11'
-          distribution: 'temurin'
+          java-version: '21'
+          distribution: 'corretto'
           check-latest: true
       # Configure Gradle for optimal use in GiHub Actions, including caching of downloaded dependencies.
       # See: https://github.com/gradle/actions/blob/main/setup-gradle/README.md
diff --git a/build.gradle b/build.gradle
index 3edf4f8..e542776 100644
--- a/build.gradle
+++ b/build.gradle
@@ -14,10 +14,10 @@ plugins {
     id 'io.github.gradle-nexus.publish-plugin' version '2.0.0'
     id 'com.github.ben-manes.versions' version '0.52.0'
     id "me.champeau.jmh" version "0.7.3"
-    id "net.ltgt.errorprone" version '4.2.0'
+    id "net.ltgt.errorprone" version '4.3.0'
 
     // Kotlin just for tests - not production code
-    id 'org.jetbrains.kotlin.jvm' version '2.2.0'
+    id 'org.jetbrains.kotlin.jvm' version '2.2.10'
 }
 
 java {
@@ -96,8 +96,8 @@ dependencies {
     jmh 'org.openjdk.jmh:jmh-core:1.37'
     jmh 'org.openjdk.jmh:jmh-generator-annprocess:1.37'
 
-    errorprone 'com.uber.nullaway:nullaway:0.12.7'
-    errorprone 'com.google.errorprone:error_prone_core:2.37.0'
+    errorprone 'com.uber.nullaway:nullaway:0.12.8'
+    errorprone 'com.google.errorprone:error_prone_core:2.41.0'
 
     // just tests
     testCompileOnly 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
diff --git a/settings.gradle b/settings.gradle
index d5a82f4..d1e33ac 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -1,6 +1,6 @@
 plugins {
-    id 'com.gradle.develocity' version '4.0.2'
-    id 'org.gradle.toolchains.foojay-resolver-convention' version '0.9.0'
+    id 'com.gradle.develocity' version '4.1'
+    id 'org.gradle.toolchains.foojay-resolver-convention' version '1.0.0'
 }
 
 develocity {
diff --git a/src/main/java/org/dataloader/ValueCache.java b/src/main/java/org/dataloader/ValueCache.java
index 80c8402..b06fdb8 100644
--- a/src/main/java/org/dataloader/ValueCache.java
+++ b/src/main/java/org/dataloader/ValueCache.java
@@ -3,6 +3,7 @@
 import org.dataloader.annotations.PublicSpi;
 import org.dataloader.impl.CompletableFutureKit;
 import org.dataloader.impl.NoOpValueCache;
+import org.jspecify.annotations.Nullable;
 import org.jspecify.annotations.NullMarked;
 
 import java.util.ArrayList;
@@ -40,7 +41,7 @@
  */
 @PublicSpi
 @NullMarked
-public interface ValueCache<K, V> {
+public interface ValueCache<K, V extends @Nullable Object> {
 
     /**
      * Creates a new value cache, using the default no-op implementation.
diff --git a/src/test/kotlin/org/dataloader/KotlinExamples.kt b/src/test/kotlin/org/dataloader/KotlinExamples.kt
index 480a965..f53faf4 100644
--- a/src/test/kotlin/org/dataloader/KotlinExamples.kt
+++ b/src/test/kotlin/org/dataloader/KotlinExamples.kt
@@ -1,8 +1,10 @@
 package org.dataloader
 
+import java.util.concurrent.CompletableFuture
 import org.junit.jupiter.api.Test
 import reactor.core.publisher.Flux
 import java.util.concurrent.CompletableFuture.completedFuture
+import org.dataloader.impl.NoOpValueCache
 
 /**
  * Some Kotlin code to prove that are JSpecify annotations work here
@@ -81,6 +83,19 @@ class KotlinExamples {
         standardNullableAsserts(dataLoader)
     }
 
+    @Test
+    fun `basic kotlin test of nullable value types in value cache`() {
+        val valueCache = object : ValueCache<String, String?> by NoOpValueCache() {
+            override fun get(key: String): CompletableFuture<String?> = if (key == "null")
+                completedFuture(null)
+            else
+                completedFuture(key)
+        }
+
+        assert(valueCache["key"].get() == "key")
+        assert(valueCache["null"].get() == null)
+    }
+
     private fun standardNullableAsserts(dataLoader: DataLoader<String, String?>) {
         val cfA = dataLoader.load("A")
         val cfB = dataLoader.load("B")