diff --git a/builtin-add.c b/builtin-add.c
index a571473..cb6e590 100644
--- a/builtin-add.c
+++ b/builtin-add.c
@@ -198,7 +198,7 @@
 	out = open(file, O_CREAT | O_WRONLY, 0644);
 	if (out < 0)
 		die ("Could not open '%s' for writing.", file);
-	rev.diffopt.file = fdopen(out, "w");
+	rev.diffopt.file = xfdopen(out, "w");
 	rev.diffopt.close_file = 1;
 	if (run_diff_files(&rev, 0))
 		die ("Could not write patch");