diff --git a/core/src/test/java/org/apache/cxf/io/CachedStreamTestBase.java b/core/src/test/java/org/apache/cxf/io/CachedStreamTestBase.java
index cdde133cb50..3fd64d4a690 100755
--- a/core/src/test/java/org/apache/cxf/io/CachedStreamTestBase.java
+++ b/core/src/test/java/org/apache/cxf/io/CachedStreamTestBase.java
@@ -240,6 +240,7 @@ public void testUseBusProps() throws Exception {
             EasyMock.expect(b.getProperty(CachedConstants.CIPHER_TRANSFORMATION_BUS_PROP)).andReturn(null);
             Path tmpDirPath = Files.createTempDirectory("temp-dir");
             EasyMock.expect(b.getProperty(CachedConstants.OUTPUT_DIRECTORY_BUS_PROP)).andReturn(tmpDirPath.toString());
+            EasyMock.expect(b.getExtension(CachedOutputStreamCleaner.class)).andReturn(null).anyTimes();
 
             BusFactory.setThreadDefaultBus(b);