diff --git a/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtension.java b/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtension.java
index e8bdb612d..e9f985445 100644
--- a/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtension.java
+++ b/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtension.java
@@ -54,8 +54,6 @@ public boolean isEnabled(ExtensionParameters parameters)
     @Override
     public void check(Root rootNode, ExtensionParameters parameters) throws ZserioExtensionException
     {
-        CppExtensionParameters.check(parameters);
-
         final CompatibilityChecker compatibilityChecker = new CompatibilityChecker();
         rootNode.walk(compatibilityChecker);
 
diff --git a/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtensionParameters.java b/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtensionParameters.java
index 20b10d9e0..37a6bb9ea 100644
--- a/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtensionParameters.java
+++ b/compiler/extensions/cpp/src/zserio/extension/cpp/CppExtensionParameters.java
@@ -17,8 +17,10 @@
  */
 public final class CppExtensionParameters
 {
-    public CppExtensionParameters(ExtensionParameters parameters)
+    public CppExtensionParameters(ExtensionParameters parameters) throws ZserioExtensionException
     {
+        check(parameters);
+
         outputDir = parameters.getCommandLineArg(OptionCpp);
         withWriterCode = parameters.getWithWriterCode();
         withPubsubCode = parameters.getWithPubsubCode();
@@ -187,7 +189,7 @@ static boolean hasOptionCpp(ExtensionParameters parameters)
         return parameters.argumentExists(OptionCpp);
     }
 
-    static void check(ExtensionParameters parameters) throws ZserioExtensionException
+    private void check(ExtensionParameters parameters) throws ZserioExtensionException
     {
         final String cppAllocator = parameters.getCommandLineArg(OptionSetCppAllocator);
         if (cppAllocator != null && !cppAllocator.equals(StdAllocator) &&
diff --git a/compiler/extensions/cpp/test/zserio/extension/cpp/CppExtensionParametersTest.java b/compiler/extensions/cpp/test/zserio/extension/cpp/CppExtensionParametersTest.java
index 943808453..f0e53af2c 100644
--- a/compiler/extensions/cpp/test/zserio/extension/cpp/CppExtensionParametersTest.java
+++ b/compiler/extensions/cpp/test/zserio/extension/cpp/CppExtensionParametersTest.java
@@ -23,7 +23,7 @@ public void checkUnknownSetCppAllocator()
         final boolean withTypeInfoCode = false;
         final TestExtensionParameters extensionParameters = new TestExtensionParameters(
                 setCppAllocator, withReflectionCode, withWriterCode, withTypeInfoCode);
-        assertThrows(ZserioExtensionException.class, () -> CppExtensionParameters.check(extensionParameters));
+        assertThrows(ZserioExtensionException.class, () -> new CppExtensionParameters(extensionParameters));
     }
 
     @Test
@@ -35,7 +35,7 @@ public void checkStdSetCppAllocator()
         final boolean withTypeInfoCode = false;
         final TestExtensionParameters extensionParameters = new TestExtensionParameters(
                 setCppAllocator, withReflectionCode, withWriterCode, withTypeInfoCode);
-        assertDoesNotThrow(() -> CppExtensionParameters.check(extensionParameters));
+        assertDoesNotThrow(() -> new CppExtensionParameters(extensionParameters));
     }
 
     @Test
@@ -47,7 +47,7 @@ public void checkPolymorphicSetCppAllocator()
         final boolean withTypeInfoCode = false;
         final TestExtensionParameters extensionParameters = new TestExtensionParameters(
                 setCppAllocator, withReflectionCode, withWriterCode, withTypeInfoCode);
-        assertDoesNotThrow(() -> CppExtensionParameters.check(extensionParameters));
+        assertDoesNotThrow(() -> new CppExtensionParameters(extensionParameters));
     }
 
     @Test
@@ -59,7 +59,7 @@ public void checkWithReflectionCode()
         final boolean withTypeInfoCode = true;
         final TestExtensionParameters extensionParameters = new TestExtensionParameters(
                 setCppAllocator, withReflectionCode, withWriterCode, withTypeInfoCode);
-        assertDoesNotThrow(() -> CppExtensionParameters.check(extensionParameters));
+        assertDoesNotThrow(() -> new CppExtensionParameters(extensionParameters));
     }
 
     @Test
@@ -71,7 +71,7 @@ public void checkWithReflectionCodeWithoutTypeInfoCode()
         final boolean withTypeInfoCode = false;
         final TestExtensionParameters extensionParameters = new TestExtensionParameters(
                 setCppAllocator, withReflectionCode, withWriterCode, withTypeInfoCode);
-        assertThrows(ZserioExtensionException.class, () -> CppExtensionParameters.check(extensionParameters));
+        assertThrows(ZserioExtensionException.class, () -> new CppExtensionParameters(extensionParameters));
     }
 
     private static class TestExtensionParameters implements ExtensionParameters
@@ -94,8 +94,12 @@ public boolean argumentExists(String argumentName)
                 return withWriterCode;
             if (argumentName.equals("withTypeInfoCode"))
                 return withTypeInfoCode;
+            if (argumentName.equals("withoutSourcesAmalgamation"))
+                return false;
+            if (argumentName.equals("withParsingInfoCode"))
+                return false;
 
-            fail("TestExtensionParameters: argumentExists failure!");
+            fail("TestExtensionParameters: argumentExists failure for '" + argumentName + "'!");
 
             return false;
         }
@@ -105,8 +109,10 @@ public String getCommandLineArg(String argumentName)
         {
             if (argumentName.equals("setCppAllocator"))
                 return setCppAllocator;
+            if (argumentName.equals("cpp"))
+                return null;
 
-            fail("TestExtensionParameters: getCommandLineArg failure!");
+            fail("TestExtensionParameters: getCommandLineArg failure for '" + argumentName + "'!");
 
             return null;
         }