diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index 4318f84d53..673baa5c3c 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -8,6 +8,10 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 . "$TEST_DIRECTORY"/lib-bundle.sh
 . "$TEST_DIRECTORY"/lib-bitmap.sh
 
+# t5310 deals only with single-pack bitmaps, so don't write MIDX bitmaps in
+# their place.
+GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0
+
 objpath () {
 	echo ".git/objects/$(echo "$1" | sed -e 's|\(..\)|\1/|')"
 }