diff --git a/src/test/org/apache/commons/lang/reflect/MethodUtilsTest.java b/src/test/org/apache/commons/lang/reflect/MethodUtilsTest.java
index 5965f8eeb..dac6aeb4c 100644
--- a/src/test/org/apache/commons/lang/reflect/MethodUtilsTest.java
+++ b/src/test/org/apache/commons/lang/reflect/MethodUtilsTest.java
@@ -87,7 +87,7 @@ public String foo(Object o) {
         }
     }
 
-    private static class TestMutable implements Mutable {
+    private static class TestMutable implements Mutable<Object> {
         public Object getValue() {
             return null;
         }