diff --git a/buildSrc/src/main/groovy/io.deephaven.java-toolchain-conventions.gradle b/buildSrc/src/main/groovy/io.deephaven.java-toolchain-conventions.gradle
index 2a1322225bc..6c2f2a91fb5 100644
--- a/buildSrc/src/main/groovy/io.deephaven.java-toolchain-conventions.gradle
+++ b/buildSrc/src/main/groovy/io.deephaven.java-toolchain-conventions.gradle
@@ -4,15 +4,15 @@ plugins {
   id 'java'
 }
 
-def compilerVersion = Integer.parseInt((String)project.findProperty('compilerVersion') ?: '11')
+def compilerVersion = Integer.parseInt((String)project.findProperty('compilerVersion') ?: '21')
 def compilerVendor = project.hasProperty('compilerVendor') ?  JvmVendorSpec.matching((String)project.property('compilerVendor')): null
 
 def languageLevel = Integer.parseInt((String)project.findProperty('languageLevel') ?: '11')
-def runtimeVersion = Integer.parseInt((String)project.findProperty('runtimeVersion') ?: '11')
+def runtimeVersion = Integer.parseInt((String)project.findProperty('runtimeVersion') ?: '21')
 def runtimeVendor = project.hasProperty('runtimeVendor') ?  JvmVendorSpec.matching((String)project.property('runtimeVendor')): null
 
 def testLanguageLevel = Integer.parseInt((String)project.findProperty('testLanguageLevel') ?: '11')
-def testRuntimeVersion = Integer.parseInt((String)project.findProperty('testRuntimeVersion') ?: '11')
+def testRuntimeVersion = Integer.parseInt((String)project.findProperty('testRuntimeVersion') ?: '21')
 def testRuntimeVendor = project.hasProperty('testRuntimeVendor') ?  JvmVendorSpec.matching((String)project.property('testRuntimeVendor')): null
 
 if (languageLevel > compilerVersion) {
@@ -82,10 +82,14 @@ tasks.withType(JavaCompile).configureEach {
   if (name == 'compileTestJava') {
     if (compilerVersion != testLanguageLevel) {
       options.release.set testLanguageLevel
+      sourceCompatibility = testLanguageLevel
+      targetCompatibility = testLanguageLevel
     }
   } else {
     if (compilerVersion != languageLevel) {
       options.release.set languageLevel
+      sourceCompatibility = languageLevel
+      targetCompatibility = languageLevel
     }
   }
 }
diff --git a/clock-impl/build.gradle b/clock-impl/build.gradle
index b7af62787ed..06e5a378705 100644
--- a/clock-impl/build.gradle
+++ b/clock-impl/build.gradle
@@ -12,8 +12,10 @@ dependencies {
 
 tasks.withType(JavaCompile).configureEach {
     options.compilerArgs += ['--add-exports', 'java.base/jdk.internal.misc=ALL-UNNAMED']
-    // Explicitly set the source compatibility so gradle will invoke javac with `-source 11` instead of `--release`
-    sourceCompatibility = 11
+    // Explicitly unset release so gradle will invoke javac with `-source <languageLevel> -target <languageLevel>`
+    // instead of `--release <languageLevel>`, which would otherwise produce
+    // > error: exporting a package from system module java.base is not allowed with --release
+    options.release.unset()
 }
 
 tasks.withType(Javadoc).configureEach {
diff --git a/hotspot-impl/build.gradle b/hotspot-impl/build.gradle
index 65562498d26..006834795e4 100644
--- a/hotspot-impl/build.gradle
+++ b/hotspot-impl/build.gradle
@@ -12,8 +12,10 @@ dependencies {
 
 tasks.withType(JavaCompile).configureEach {
     options.compilerArgs += ['--add-exports', 'java.management/sun.management=ALL-UNNAMED']
-    // Explicitly set the source compatibility so gradle will invoke javac with `-source 11` instead of `--release`
-    sourceCompatibility = 11
+    // Explicitly unset release so gradle will invoke javac with `-source <languageLevel> -target <languageLevel>`
+    // instead of `--release <languageLevel>`, which would otherwise produce
+    // > error: exporting a package from system module java.management is not allowed with --release
+    options.release.unset()
 }
 
 tasks.withType(Javadoc).configureEach {