diff --git a/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java b/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
index ebf3c7f60c8..f64c9595714 100755
--- a/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
+++ b/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
@@ -231,7 +231,7 @@ public class TestIndexWriterMergePolicy extends LuceneTestCase {
         numSegments++;
       } else {
         if (upperBound * mergeFactor <= maxMergeDocs) {
-          assertTrue("numSegments=" + numSegments + " vs mergeFactor=" + mergeFactor, numSegments < mergeFactor);
+          assertTrue("maxMergeDocs=" + maxMergeDocs + "; numSegments=" + numSegments + "; upperBound=" + upperBound + "; mergeFactor=" + mergeFactor, numSegments < mergeFactor);
         }
 
         do {