diff --git a/ChangeLog b/ChangeLog
index 8a73844365..f73d193e75 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Oct 16 00:07:06 2001  Nobuyoshi Nakada  <nobu.nakada@nifty.ne.jp>
+
+	* parse.y (yylex): disallow alpha-numeric and mbchar for
+	  terminator of %string.
+
 Wed Oct 10 03:11:47 2001  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* file.c (rb_stat_clone): should copy internal data too.
diff --git a/parse.y b/parse.y
index d7ed5b5f58..b1147fc97d 100644
--- a/parse.y
+++ b/parse.y
@@ -3528,6 +3528,10 @@ yylex()
 	    }
 	    else {
 		term = nextc();
+		if (ISALNUM(term) || ismbchar(term)) {
+		    yyerror("unknown type of %string");
+		    return 0;
+		}
 	    }
 	    if (c == -1 || term == -1) {
 		rb_compile_error("unterminated quoted string meets end of file");