diff --git a/src/Renderer/Pdf.php b/src/Renderer/Pdf.php
index 51ae208..a60fc67 100644
--- a/src/Renderer/Pdf.php
+++ b/src/Renderer/Pdf.php
@@ -55,19 +55,14 @@ class Pdf extends AbstractRenderer
     protected $moduleSize = 0.5;
 
     /**
-     * Set an image resource to draw the barcode inside
-     * @param resource $value
-     * @return \Zend\Barcode\Renderer
-     * @throw  Exception
+     * Set a PDF resource to draw the barcode inside
+     *
+     * @param PdfDocument $pdf
+     * @param integer     $page
+     * @return Pdf
      */
-    public function setResource($pdf, $page = 0)
+    public function setResource(PdfDocument $pdf, $page = 0)
     {
-        if (!$pdf instanceof PdfDocument) {
-            throw new Exception\InvalidArgumentException(
-                'Invalid Zend\Pdf\PdfDocument resource provided to setResource()'
-            );
-        }
-
         $this->resource = $pdf;
         $this->page     = intval($page);