diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
index dcadd56d3a..79592a3b0a 100755
--- a/t/t5510-fetch.sh
+++ b/t/t5510-fetch.sh
@@ -169,6 +169,7 @@ test_expect_success REFFILES 'fetch --prune fails to delete branches' '
 	git clone . prune-fail &&
 	cd prune-fail &&
 	git update-ref refs/remotes/origin/extrabranch main &&
+	git pack-refs --all &&
 	: this will prevent --prune from locking packed-refs for deleting refs, but adding loose refs still succeeds  &&
 	>.git/packed-refs.new &&