diff --git a/src/CartItem.php b/src/CartItem.php
index 1ef6cbe..9b22b1d 100644
--- a/src/CartItem.php
+++ b/src/CartItem.php
@@ -74,7 +74,7 @@ class CartItem
     {
         if(empty($id)) throw new \InvalidArgumentException('Please supply a valid identifier.');
         if(empty($name)) throw new \InvalidArgumentException('Please supply a valid name.');
-        if(empty($price) || ! is_numeric($price))
+        if(strlen($price) < 0 || ! is_numeric($price))
             throw new \InvalidArgumentException('Please supply a valid price.');
 
         $this->id = $id;
@@ -268,4 +268,4 @@ class CartItem
 
         return md5($id . serialize($options));
     }
-}
\ No newline at end of file
+}