diff --git a/pmd-test/src/main/java/net/sourceforge/pmd/ant/AbstractAntTestHelper.java b/pmd-test/src/main/java/net/sourceforge/pmd/ant/AbstractAntTestHelper.java
index 58455b3c4a..10e2304e4b 100644
--- a/pmd-test/src/main/java/net/sourceforge/pmd/ant/AbstractAntTestHelper.java
+++ b/pmd-test/src/main/java/net/sourceforge/pmd/ant/AbstractAntTestHelper.java
@@ -180,7 +180,7 @@ public abstract class AbstractAntTestHelper {
         return result.replace(System.lineSeparator(), "\n");
     }
 
-    private class AntBuildListener extends DefaultLogger {
+    private final class AntBuildListener extends DefaultLogger {
         private AntBuildListener() {
             msgOutputLevel = Project.MSG_INFO;
         }