diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 83abe5f25e..8a8b0f1aba 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -272,7 +272,8 @@ test_expect_success \
 
 test_expect_success \
     'make sure index-pack detects the SHA1 collision' \
-    'test_must_fail git-index-pack -o bad.idx test-3.pack'
+    'test_must_fail git-index-pack -o bad.idx test-3.pack 2>msg &&
+     grep "SHA1 COLLISION FOUND" msg'
 
 test_expect_success \
     'honor pack.packSizeLimit' \