diff --git a/builtin/mailsplit.c b/builtin/mailsplit.c
index 264df6259a..0993418e63 100644
--- a/builtin/mailsplit.c
+++ b/builtin/mailsplit.c
@@ -225,14 +225,14 @@ static int split_mbox(const char *file, const char *dir, int allow_bare,
 	FILE *f = !strcmp(file, "-") ? stdin : fopen(file, "r");
 	int file_done = 0;
 
-	if (isatty(fileno(f)))
-		warning(_("reading patches from stdin/tty..."));
-
 	if (!f) {
 		error_errno("cannot open mbox %s", file);
 		goto out;
 	}
 
+	if (isatty(fileno(f)))
+		warning(_("reading patches from stdin/tty..."));
+
 	do {
 		peek = fgetc(f);
 		if (peek == EOF) {