diff --git a/t/helper/test-mktemp.c b/t/helper/test-mktemp.c
index 2290688940..da195640a9 100644
--- a/t/helper/test-mktemp.c
+++ b/t/helper/test-mktemp.c
@@ -6,10 +6,16 @@
 
 int cmd__mktemp(int argc, const char **argv)
 {
+	char *template;
+	int fd;
+
 	if (argc != 2)
 		usage("Expected 1 parameter defining the temporary file template");
+	template = xstrdup(argv[1]);
 
-	xmkstemp(xstrdup(argv[1]));
+	fd = xmkstemp(template);
 
+	close(fd);
+	free(template);
 	return 0;
 }