diff --git a/ChangeLog b/ChangeLog
index 18fa6b62d3..2616a46241 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 31 02:17:54 2010  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* insns.def (defined): respond_to_missing? may not be available
+	  (for BasicObject instances).
+
 Mon May 31 01:43:42 2010  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
 
 	* lib/delegate: Delegator: combine (public|protected) methods with
diff --git a/insns.def b/insns.def
index 23c0143907..f75007dca2 100644
--- a/insns.def
+++ b/insns.def
@@ -799,8 +799,15 @@ defined
 		}
 	    }
 	}
-	if (RTEST(rb_funcall(v, rb_intern("respond_to_missing?"), 2, obj, Qfalse)))
-	    expr_type = "method";
+	{
+	    VALUE args[2];
+	    VALUE r;
+
+	    args[0] = obj; args[1] = Qfalse;
+	    r = rb_check_funcall(v, rb_intern("respond_to_missing?"), 2, args);
+	    if (r != Qundef && RTEST(r)) 
+		expr_type = "method";
+	}
 	break;
       }
       case DEFINED_YIELD: