diff --git a/t/t3403-rebase-skip.sh b/t/t3403-rebase-skip.sh
index 3968020e64..1f5122b632 100755
--- a/t/t3403-rebase-skip.sh
+++ b/t/t3403-rebase-skip.sh
@@ -67,7 +67,7 @@ test_expect_success 'rebase --skip with --merge' '
 '
 
 test_expect_success 'merge and reference trees equal' '
-	test -z "`git diff-tree skip-merge skip-reference`"
+	test -z "$(git diff-tree skip-merge skip-reference)"
 '
 
 test_expect_success 'moved back to branch correctly' '