diff --git a/file.c b/file.c
index c23e92d22e..112d9b3e4d 100644
--- a/file.c
+++ b/file.c
@@ -5019,7 +5019,7 @@ rb_file_s_basename(int argc, VALUE *argv, VALUE _)
 {
     VALUE fname, fext;
     const char *name, *p;
-    long f, n;
+    long f = 0, n;
     rb_encoding *enc;
 
     fext = Qnil;