diff --git a/src/Storage/Part.php b/src/Storage/Part.php
index 73936dc5..33a3747f 100644
--- a/src/Storage/Part.php
+++ b/src/Storage/Part.php
@@ -198,7 +198,7 @@ protected function _cacheContent()
         }
         $counter = 1;
         foreach ($parts as $part) {
-            $this->parts[$counter++] = new self(array('headers' => $part['header'], 'content' => $part['body']));
+            $this->parts[$counter++] = new static(array('headers' => $part['header'], 'content' => $part['body']));
         }
     }
 
diff --git a/src/Storage/Part/File.php b/src/Storage/Part/File.php
index e11d8209..a7b9d7a6 100644
--- a/src/Storage/Part/File.php
+++ b/src/Storage/Part/File.php
@@ -155,7 +155,7 @@ public function getPart($num)
             throw new Exception\RuntimeException('part not found');
         }
 
-        return new self(array('file' => $this->fh, 'startPos' => $this->partPos[$num][0],
+        return new static(array('file' => $this->fh, 'startPos' => $this->partPos[$num][0],
                               'endPos' => $this->partPos[$num][1]));
     }
 }