diff --git a/ChangeLog b/ChangeLog
index 60aaa33ae5..2370cd14b9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Apr 19 19:18:53 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (parser_yylex): reduced duplicated conditions.
+
 Mon Apr 19 13:58:04 2010  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/rdoc:  Update to RDoc 2.5.4.  Fixes #3169, #3160, #3023.
diff --git a/parse.y b/parse.y
index 77f3e0a4f1..0ba786c939 100644
--- a/parse.y
+++ b/parse.y
@@ -6117,7 +6117,7 @@ arg_ambiguous_gen(struct parser_params *parser)
     dispatch0(arg_ambiguous);
 #endif
 }
-#define arg_ambiguous() arg_ambiguous_gen(parser)
+#define arg_ambiguous() (arg_ambiguous_gen(parser), 1)
 
 static ID
 formal_argument_gen(struct parser_params *parser, ID lhs)
@@ -6886,8 +6886,7 @@ parser_yylex(struct parser_params *parser)
 	    lex_state = EXPR_BEG;
 	    return tOP_ASGN;
 	}
-	if (IS_BEG() || IS_SPCARG(c)) {
-	    if (!IS_BEG()) arg_ambiguous();
+	if (IS_BEG() || (IS_SPCARG(c) && arg_ambiguous())) {
 	    lex_state = EXPR_BEG;
 	    pushback(c);
 	    if (c != -1 && ISDIGIT(c)) {
@@ -6919,8 +6918,7 @@ parser_yylex(struct parser_params *parser)
 	    lex_state = EXPR_ARG;
 	    return tLAMBDA;
 	}
-	if (IS_BEG() || IS_SPCARG(c)) {
-	    if (!IS_BEG()) arg_ambiguous();
+	if (IS_BEG() || (IS_SPCARG(c) && arg_ambiguous())) {
 	    lex_state = EXPR_BEG;
 	    pushback(c);
 	    if (c != -1 && ISDIGIT(c)) {