diff --git a/lib/Less/Parser.php b/lib/Less/Parser.php
index 2c9d8790..155c8e07 100644
--- a/lib/Less/Parser.php
+++ b/lib/Less/Parser.php
@@ -926,7 +926,7 @@ public function skipWhitespace($length){
 	public function expect($tok, $msg = NULL) {
 		$result = $this->match( array($tok) );
 		if (!$result) {
-			$this->Error( $msg	? "Expected '" . $tok . "' got '" . $this->input[$this->pos] . "'" : $msg );
+			$this->Error( !$msg	? "Expected '" . $tok . "' got '" . $this->input[$this->pos] . "'" : $msg );
 		} else {
 			return $result;
 		}