diff --git a/lib/CurlResponse.php b/lib/CurlResponse.php
index 02a9eec..b6922e9 100644
--- a/lib/CurlResponse.php
+++ b/lib/CurlResponse.php
@@ -53,6 +53,7 @@ public function getHeaders()
      */
     public function getHeader($key)
     {
+        $key = strtolower($key);
         return isset($this->headers[$key]) ? $this->headers[$key] : null;
     }