diff --git a/src/Knp/Snappy/AbstractGenerator.php b/src/Knp/Snappy/AbstractGenerator.php
index 19d4e0d3..92b5c935 100644
--- a/src/Knp/Snappy/AbstractGenerator.php
+++ b/src/Knp/Snappy/AbstractGenerator.php
@@ -43,7 +43,7 @@ public function __construct($binary, array $options = array(), array $env = null
 
         $this->setBinary($binary);
         $this->setOptions($options);
-        $this->env = $env;
+        $this->env = empty($env) ? null : $env;
     }
 
     public function __destruct()
@@ -361,7 +361,7 @@ protected function createTemporaryFile($content = null, $extension = null)
         if (null !== $content) {
             file_put_contents($filename, $content);
         }
-        
+
         $this->temporaryFiles[] = $filename;
 
         return $filename;