diff --git a/ChangeLog b/ChangeLog
index b8959a1fe2..840f2d49c7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul 22 19:05:47 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (rb_enc_symname2_p): get rid of potential out-of-bound
+	  access.
+
 Fri Jul 22 13:55:59 2011  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/net/http.rb:  Net::HTTP#finish is used to manually close
diff --git a/parse.y b/parse.y
index aca2b6ac3e..f822bac773 100644
--- a/parse.y
+++ b/parse.y
@@ -9685,7 +9685,7 @@ rb_enc_symname2_p(const char *name, long len, rb_encoding *enc)
     const char *e = m + len;
     int localid = FALSE;
 
-    if (!m) return FALSE;
+    if (!m || len <= 0) return FALSE;
     switch (*m) {
       case '\0':
 	return FALSE;
@@ -9738,8 +9738,8 @@ rb_enc_symname2_p(const char *name, long len, rb_encoding *enc)
 	break;
 
       case '!':
+	if (len == 1) return FALSE;
 	switch (*++m) {
-	  case '\0': return TRUE;
 	  case '=': case '~': ++m; break;
 	  default: return FALSE;
 	}