diff --git a/.classpath b/.classpath
index 67dc756..5f1c5c8 100644
--- a/.classpath
+++ b/.classpath
@@ -13,7 +13,7 @@
 			<attribute name="test" value="true"/>
 		</attributes>
 	</classpathentry>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-20">
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
 		<attributes>
 			<attribute name="maven.pomderived" value="true"/>
 		</attributes>
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index cf56893..78adf50 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -9,7 +9,7 @@ jobs:
     strategy:
       matrix:
         # Build with all versions that can load the nashorn standalone Jar:
-        java: [ 20 ]
+        java: [ 17, 20 ]
     name: Java ${{ matrix.java }} build
     steps:
       - uses: actions/checkout@v2
@@ -30,7 +30,7 @@ jobs:
     strategy:
       matrix:
         # test against latest update of each major Java version, as well as specific updates of LTS versions:
-        java: [ 20 ]
+        java: [ 17, 20 ]
     name: Java ${{ matrix.java }} test
     steps:
       - uses: actions/download-artifact@v2
diff --git a/.settings/org.eclipse.jdt.core.prefs b/.settings/org.eclipse.jdt.core.prefs
index 70bf2fd..99a63d5 100644
--- a/.settings/org.eclipse.jdt.core.prefs
+++ b/.settings/org.eclipse.jdt.core.prefs
@@ -1,9 +1,9 @@
 eclipse.preferences.version=1
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=20
-org.eclipse.jdt.core.compiler.compliance=20
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
+org.eclipse.jdt.core.compiler.compliance=11
 org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
 org.eclipse.jdt.core.compiler.problem.forbiddenReference=warning
 org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=ignore
 org.eclipse.jdt.core.compiler.processAnnotations=disabled
 org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=20
+org.eclipse.jdt.core.compiler.source=11
diff --git a/README.md b/README.md
index c55d198..884859d 100644
--- a/README.md
+++ b/README.md
@@ -112,6 +112,7 @@ for JS evaluation and better handling of monitoring for threads for possible CPU
 
 ## Version History
 
+- 0.4.2: Ensure compatibility with Java 17
 - 0.4.0: Upgrade to Java 20
 - 0.3.2: Updating JSBeautifier dependency ([PR #143](https://github.com/javadelight/delight-nashorn-sandbox/pull/143) by [davejbur](https://github.com/davejbur))
 - 0.3.1: Protect against RegEx attacks in sanitising script input by [PR #139](https://github.com/javadelight/delight-nashorn-sandbox/pull/139)
diff --git a/pom.xml b/pom.xml
index e8949ad..0261560 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
 
 	<groupId>org.javadelight</groupId>
 	<artifactId>delight-nashorn-sandbox</artifactId>
-	<version>0.4.1</version>
+	<version>0.4.2</version>
 	<description>A safe sandbox to execute JavaScript code from Nashorn.</description>
 	<url>https://github.com/javadelight/delight-nashorn-sandbox</url>
 
@@ -132,7 +132,7 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>3.11.0</version>
 				<configuration>
-				  <release>20</release>
+				  <release>11</release>
 				</configuration>
 			</plugin>