diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index 2d22a17c4a..a8f530676c 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -9,7 +9,8 @@ objpath () {
 
 # show objects present in pack ($1 should be associated *.idx)
 list_packed_objects () {
-	git show-index <"$1" | cut -d' ' -f2
+	git show-index <"$1" >object-list &&
+	cut -d' ' -f2 object-list
 }
 
 # has_any pattern-file content-file
@@ -204,8 +205,8 @@ test_expect_success 'pack-objects to file can use bitmap' '
 	# verify equivalent packs are generated with/without using bitmap index
 	packasha1=$(git pack-objects --no-use-bitmap-index --all packa </dev/null) &&
 	packbsha1=$(git pack-objects --use-bitmap-index --all packb </dev/null) &&
-	list_packed_objects <packa-$packasha1.idx >packa.objects &&
-	list_packed_objects <packb-$packbsha1.idx >packb.objects &&
+	list_packed_objects packa-$packasha1.idx >packa.objects &&
+	list_packed_objects packb-$packbsha1.idx >packb.objects &&
 	test_cmp packa.objects packb.objects
 '