diff --git a/t/t1304-default-acl.sh b/t/t1304-default-acl.sh
index 79045abb51..f5422f1d33 100755
--- a/t/t1304-default-acl.sh
+++ b/t/t1304-default-acl.sh
@@ -26,7 +26,7 @@ test_expect_success 'checking for a working acl setup' '
 
 if test -z "$LOGNAME"
 then
-	LOGNAME=$USER
+	LOGNAME="${USER:-$(id -u -n)}"
 fi
 
 check_perms_and_acl () {