diff --git a/t/test-lib.sh b/t/test-lib.sh
index c1476f9..49f06d2 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -54,6 +54,7 @@
 unset GIT_CEILING_DIRECTORIES
 unset SHA1_FILE_DIRECTORIES
 unset SHA1_FILE_DIRECTORY
+unset GIT_NOTES_REF
 GIT_MERGE_VERBOSITY=5
 export GIT_MERGE_VERBOSITY
 export GIT_AUTHOR_EMAIL GIT_AUTHOR_NAME