diff --git a/ChangeLog b/ChangeLog
index 6a7781449e..f5faefa9aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Apr 24 11:53:28 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/openssl/ossl_asn1.c (ossl_asn1_initialize): SYMID on a value
+	  other than Symbol is an undefined behavior.  fix up r31699.
+	  [ruby-core:62142] [Bug #9771]
+
 Thu Apr 24 11:21:37 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* parse.y (rb_sym2id, rb_sym2id_without_pindown): return 0 for
diff --git a/ext/openssl/ossl_asn1.c b/ext/openssl/ossl_asn1.c
index c2344affa6..efdfbfc8aa 100644
--- a/ext/openssl/ossl_asn1.c
+++ b/ext/openssl/ossl_asn1.c
@@ -1150,7 +1150,7 @@ ossl_asn1_initialize(int argc, VALUE *argv, VALUE self)
 	}
 	if(!SYMBOL_P(tag_class))
 	    ossl_raise(eASN1Error, "invalid tag class");
-	if(SYM2ID(tagging) == sIMPLICIT && NUM2INT(tag) > 31)
+	if(!NIL_P(tagging) && SYM2ID(tagging) == sIMPLICIT && NUM2INT(tag) > 31)
 	    ossl_raise(eASN1Error, "tag number for Universal too large");
     }
     else{