diff --git a/ChangeLog b/ChangeLog
index afd4e5d845..07ec4aad3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct 15 16:57:38 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (rb_intern3): check symbol table overflow.
+	  [ruby-core:26092]
+
 Thu Oct 15 15:14:15 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (io_encoding_set): get rid of parsing non-ascii string, and
diff --git a/parse.y b/parse.y
index 9207d15513..4005e7265f 100644
--- a/parse.y
+++ b/parse.y
@@ -9498,6 +9498,16 @@ rb_intern3(const char *name, long len, rb_encoding *enc)
       mbstr:;
     }
   new_id:
+    if (!(global_symbols.last_id << (ID_SCOPE_SHIFT+RUBY_SPECIAL_SHIFT))) {
+	if (len > 20) {
+	    rb_raise(rb_eRuntimeError, "symbol table overflow (symbol %.20s...)",
+		     name);
+	}
+	else {
+	    rb_raise(rb_eRuntimeError, "symbol table overflow (symbol %.*s)",
+		     (int)len, name);
+	}
+    }
     id |= ++global_symbols.last_id << ID_SCOPE_SHIFT;
   id_register:
     return register_symid(id, name, len, enc);
diff --git a/string.c b/string.c
index a8f2a1eee5..ca093517ab 100644
--- a/string.c
+++ b/string.c
@@ -6510,25 +6510,10 @@ VALUE
 rb_str_intern(VALUE s)
 {
     VALUE str = RB_GC_GUARD(s);
-    VALUE sym;
-    ID id, id2;
+    ID id;
 
     id = rb_intern_str(str);
-    sym = ID2SYM(id);
-    id2 = SYM2ID(sym);
-    if (id != id2) {
-	const char *name = rb_id2name(id2);
-
-	if (name) {
-	    rb_raise(rb_eRuntimeError, "symbol table overflow (%s given for %s)",
-		     name, RSTRING_PTR(str));
-	}
-	else {
-	    rb_raise(rb_eRuntimeError, "symbol table overflow (symbol %s)",
-		     RSTRING_PTR(str));
-	}
-    }
-    return sym;
+    return ID2SYM(id);
 }