diff --git a/datastore_server/sourceTest/java/ch/systemsx/cisd/etlserver/plugins/SimpleShufflingTest.java b/datastore_server/sourceTest/java/ch/systemsx/cisd/etlserver/plugins/SimpleShufflingTest.java
index b5c07bbdcac99c7cd6c8c7c37f5cee23415d7478..978f83e512a8b24e584cd6cf6219d81c74dcc1d6 100644
--- a/datastore_server/sourceTest/java/ch/systemsx/cisd/etlserver/plugins/SimpleShufflingTest.java
+++ b/datastore_server/sourceTest/java/ch/systemsx/cisd/etlserver/plugins/SimpleShufflingTest.java
@@ -81,7 +81,7 @@ public class SimpleShufflingTest extends AbstractFileSystemTestCase
         {
             File file = path.getFile();
             List<Long> list = freeSpace.get(file);
-            assertTrue("Unknown file " + file, list != null);
+            assertNotNull("Unknown file " + file, list);
             assertFalse("Unexpected invocation for file " + file, list.isEmpty());
             return list.remove(0);
         }