diff --git a/src/Expression.php b/src/Expression.php
index <HASH>..<HASH> 100644
--- a/src/Expression.php
+++ b/src/Expression.php
@@ -37,7 +37,7 @@ class Expression implements \ArrayAccess, \IteratorAggregate
      *
      * @var string
      */
-    protected $paramBase = ':a';
+    protected $paramBase = 'a';
 
     /**
      * Used for Linking.
@@ -356,7 +356,7 @@ class Expression implements \ArrayAccess, \IteratorAggregate
             return array_map(__METHOD__, $value);
         }
 
-        $name = $this->_paramBase;
+        $name = ':'.$this->_paramBase;
         $this->_paramBase++;
         $this->params[$name] = $value;
Fix situations where we have more than <I> parameters

PHP cycles ':a' after ':z' but 'aa' comes after 'z'.