diff --git a/setup.c b/setup.c
index 0309c27821..000ffa810e 100644
--- a/setup.c
+++ b/setup.c
@@ -134,19 +134,20 @@ int path_inside_repo(const char *prefix, const char *path)
 
 int check_filename(const char *prefix, const char *arg)
 {
-	const char *name;
 	char *to_free = NULL;
 	struct stat st;
 
 	if (starts_with(arg, ":/")) {
 		if (arg[2] == '\0') /* ":/" is root dir, always exists */
 			return 1;
-		name = arg + 2;
-	} else if (prefix)
-		name = to_free = prefix_filename(prefix, arg);
-	else
-		name = arg;
-	if (!lstat(name, &st)) {
+		arg += 2;
+		prefix = NULL;
+	}
+
+	if (prefix)
+		arg = to_free = prefix_filename(prefix, arg);
+
+	if (!lstat(arg, &st)) {
 		free(to_free);
 		return 1; /* file exists */
 	}