diff --git a/id.c b/id.c
index 57c965aff0..40c6eeb188 100644
--- a/id.c
+++ b/id.c
@@ -18,7 +18,6 @@ Init_id(void)
 {
 #undef rb_intern
 #define rb_intern(str) rb_intern_const(str)
-#define rb_intern(str) rb_intern2(str, strlen(str))
     rb_encoding *enc = rb_usascii_encoding();
 
     REGISTER_SYMID(idNULL, "");