diff --git a/src/main/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojo.java b/src/main/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojo.java
index 5159f32d..602d3b04 100644
--- a/src/main/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojo.java
+++ b/src/main/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojo.java
@@ -44,6 +44,11 @@
  */
 public abstract class AbstractCompileMojo extends AbstractGroovySourcesMojo {
 
+    /**
+     * Groovy 5.0.0-alpha-1 version.
+     */
+    protected static final Version GROOVY_5_0_0_ALPHA1 = new Version(5, 0, 0, "alpha-1");
+
     /**
      * Groovy 4.0.11 version.
      */
@@ -496,6 +501,12 @@ protected Object setupCompilerConfiguration(final File compileOutputDirectory, f
      * org.codehaus.groovy.classgen.asm.WriterController.
      */
     protected void verifyGroovyVersionSupportsTargetBytecode() {
+        if ("1.5".equals(targetBytecode) || "5".equals(targetBytecode) || "1.6".equals(targetBytecode) || "6".equals(targetBytecode) || "1.7".equals(targetBytecode) || "7".equals(targetBytecode) || "1.8".equals(targetBytecode) || "8".equals(targetBytecode) || "1.9".equals(targetBytecode) || "9".equals(targetBytecode) || "10".equals(targetBytecode)) {
+            if (groovyNewerThan(GROOVY_5_0_0_ALPHA1)) {
+                throw new IllegalArgumentException("Target bytecode " + targetBytecode + " isn't accepted by Groovy " + GROOVY_5_0_0_ALPHA1 + " or newer.");
+            }
+        }
+
         if ("21".equals(targetBytecode)) {
             if (groovyOlderThan(GROOVY_4_0_11)) {
                 throw new IllegalArgumentException("Target bytecode " + targetBytecode + " requires Groovy " + GROOVY_4_0_11 + " or newer.");
@@ -557,7 +568,7 @@ protected void verifyGroovyVersionSupportsTargetBytecode() {
         }
     }
 
-    private static String translateJavacTargetToTargetBytecode(String targetBytecode) {
+    protected static String translateJavacTargetToTargetBytecode(String targetBytecode) {
         Map<String, String> javacTargetToTargetBytecode = new HashMap<>();
         javacTargetToTargetBytecode.put("5", "1.5");
         javacTargetToTargetBytecode.put("6", "1.6");
diff --git a/src/main/java/org/codehaus/gmavenplus/mojo/AbstractGenerateStubsMojo.java b/src/main/java/org/codehaus/gmavenplus/mojo/AbstractGenerateStubsMojo.java
index 64633776..c23efa35 100644
--- a/src/main/java/org/codehaus/gmavenplus/mojo/AbstractGenerateStubsMojo.java
+++ b/src/main/java/org/codehaus/gmavenplus/mojo/AbstractGenerateStubsMojo.java
@@ -46,6 +46,11 @@
  */
 public abstract class AbstractGenerateStubsMojo extends AbstractGroovyStubSourcesMojo {
 
+    /**
+     * Groovy 5.0.0-alpha-1 version.
+     */
+    protected static final Version GROOVY_5_0_0_ALPHA1 = new Version(5, 0, 0, "alpha-1");
+
     /**
      * Groovy 4.0.11 version.
      */
@@ -417,6 +422,12 @@ protected void resetStubModifiedDates(final Set<File> stubs) {
      * org.codehaus.groovy.classgen.asm.WriterController.
      */
     protected void verifyGroovyVersionSupportsTargetBytecode() {
+        if ("1.5".equals(targetBytecode) || "5".equals(targetBytecode) || "1.6".equals(targetBytecode) || "6".equals(targetBytecode) || "1.7".equals(targetBytecode) || "7".equals(targetBytecode) || "1.8".equals(targetBytecode) || "8".equals(targetBytecode) || "1.9".equals(targetBytecode) || "9".equals(targetBytecode) || "10".equals(targetBytecode)) {
+            if (groovyNewerThan(GROOVY_5_0_0_ALPHA1)) {
+                throw new IllegalArgumentException("Target bytecode " + targetBytecode + " isn't accepted by Groovy " + GROOVY_5_0_0_ALPHA1 + " or newer.");
+            }
+        }
+
         if ("21".equals(targetBytecode)) {
             if (groovyOlderThan(GROOVY_4_0_11)) {
                 throw new IllegalArgumentException("Target bytecode " + targetBytecode + " requires Groovy " + GROOVY_4_0_11 + " or newer.");
diff --git a/src/test/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojoTest.java b/src/test/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojoTest.java
index 53ab4e6d..ac3cd286 100644
--- a/src/test/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojoTest.java
+++ b/src/test/java/org/codehaus/gmavenplus/mojo/AbstractCompileMojoTest.java
@@ -420,7 +420,7 @@ public void testUnrecognizedJava() {
     }
 
     @Test
-    public void testBytecodeTranslation() throws ClassNotFoundException, InvocationTargetException, IllegalAccessException, InstantiationException {
+    public void testBytecodeTranslation() {
         Map<String, String> expectedTranslations = new LinkedHashMap<>();
         expectedTranslations.put("5", "1.5");
         expectedTranslations.put("6", "1.6");
@@ -430,11 +430,7 @@ public void testBytecodeTranslation() throws ClassNotFoundException, InvocationT
         for (Map.Entry<String, String> entry : expectedTranslations.entrySet()) {
             String javacVersion = entry.getKey();
             String expectedGroovycVersion = entry.getValue();
-            testMojo.targetBytecode = javacVersion;
-            Class<?> compilerConfigurationClass = Class.forName("org.codehaus.groovy.control.CompilerConfiguration");
-            File compileOutputDirectory = new File(".");
-            CompilerConfiguration compilerConfiguration = (CompilerConfiguration) testMojo.setupCompilerConfiguration(compileOutputDirectory, compilerConfigurationClass);
-            assertEquals(expectedGroovycVersion, compilerConfiguration.getTargetBytecode());
+            assertEquals(expectedGroovycVersion, AbstractCompileMojo.translateJavacTargetToTargetBytecode(javacVersion));
         }
     }