diff --git a/ChangeLog b/ChangeLog
index 3d51db0fbe..df68e2893c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,11 @@ Thu Sep 30 16:11:08 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
 	* win32/win32.c (rb_w32_getenv): should return NULL if specified name
 	  is empty. a patch from Heesob Park at [ruby-core:32650]
 
+Thu Sep 30 15:18:23 2010  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* parse.y (command_asgn): allow command_call to be right hand side
+	  expression of chained assignment.  [ruby-dev:42313]
+
 Thu Sep 30 10:55:38 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* hash.c (ruby_setenv): workaround for old Windows. a patch from
diff --git a/parse.y b/parse.y
index e085088731..1c500525ec 100644
--- a/parse.y
+++ b/parse.y
@@ -690,7 +690,7 @@ static void token_info_pop(struct parser_params*, const char *token);
 %type <node> args call_args opt_call_args
 %type <node> paren_args opt_paren_args
 %type <node> command_args aref_args opt_block_arg block_arg var_ref var_lhs
-%type <node> mrhs superclass block_call block_command
+%type <node> command_asgn mrhs superclass block_call block_command
 %type <node> f_block_optarg f_block_opt
 %type <node> f_arglist f_args f_arg f_arg_item f_optarg f_marg f_marg_list f_margs
 %type <node> assoc_list assocs assoc undef_list backref string_dvar for_var
@@ -1060,15 +1060,7 @@ stmt		: keyword_alias fitem {lex_state = EXPR_FNAME;} fitem
 			$$ = dispatch1(END, $3);
 		    %*/
 		    }
-		| lhs '=' command_call
-		    {
-		    /*%%%*/
-			value_expr($3);
-			$$ = node_assign($1, $3);
-		    /*%
-			$$ = dispatch2(assign, $1, $3);
-		    %*/
-		    }
+		| command_asgn
 		| mlhs '=' command_call
 		    {
 		    /*%%%*/
@@ -1225,6 +1217,27 @@ stmt		: keyword_alias fitem {lex_state = EXPR_FNAME;} fitem
 		| expr
 		;
 
+command_asgn	: lhs '=' command_call
+		    {
+		    /*%%%*/
+			value_expr($3);
+			$$ = node_assign($1, $3);
+		    /*%
+			$$ = dispatch2(assign, $1, $3);
+		    %*/
+		    }
+		| lhs '=' command_asgn
+		    {
+		    /*%%%*/
+			value_expr($3);
+			$$ = node_assign($1, $3);
+		    /*%
+			$$ = dispatch2(assign, $1, $3);
+		    %*/
+		    }
+		;
+
+
 expr		: command_call
 		| expr keyword_and expr
 		    {