diff --git a/ChangeLog b/ChangeLog
index d8776b9070..86cc74fcd6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Apr 12 15:34:59 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* parse.y (arg): fix segfault by null caused by syntax error.
+	  [ruby-core:68851] [Bug #10957]
+
 Sun Apr 12 15:11:16 2015  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
 
 	* lib/rubygems/test_case.rb: use explicitly exception class and reverted
diff --git a/parse.y b/parse.y
index 18116f22af..7e85d70c1e 100644
--- a/parse.y
+++ b/parse.y
@@ -2103,7 +2103,7 @@ arg		: lhs '=' arg
 			value_expr($3);
 			$$ = NEW_DOT2($1, $3);
 			if ($1 && nd_type($1) == NODE_LIT && FIXNUM_P($1->nd_lit) &&
-			    nd_type($3) == NODE_LIT && FIXNUM_P($3->nd_lit)) {
+			    $3 && nd_type($3) == NODE_LIT && FIXNUM_P($3->nd_lit)) {
 			    deferred_nodes = list_append(deferred_nodes, $$);
 			}
 		    /*%
@@ -2117,7 +2117,7 @@ arg		: lhs '=' arg
 			value_expr($3);
 			$$ = NEW_DOT3($1, $3);
 			if ($1 && nd_type($1) == NODE_LIT && FIXNUM_P($1->nd_lit) &&
-			    nd_type($3) == NODE_LIT && FIXNUM_P($3->nd_lit)) {
+			    $3 && nd_type($3) == NODE_LIT && FIXNUM_P($3->nd_lit)) {
 			    deferred_nodes = list_append(deferred_nodes, $$);
 			}
 		    /*%
diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index ace5c8d46e..0274a11e83 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -561,6 +561,8 @@ eom
     bug10957 = '[ruby-core:68477] [Bug #10957]'
     assert_ruby_status(['-c', '-e', 'p ()..0'], "", bug10957)
     assert_ruby_status(['-c', '-e', 'p ()...0'], "", bug10957)
+    assert_syntax_error('0..%w.', /unterminated string/, bug10957)
+    assert_syntax_error('0...%w.', /unterminated string/, bug10957)
   end
 
   private