diff --git a/imageapi.module b/imageapi.module
index 388c7db..c86c0bf 100644
--- a/imageapi.module
+++ b/imageapi.module
@@ -186,7 +186,7 @@ function imageapi_toolkit_invoke($method, &$image, array $params = array()) {
  * @return
  *   TRUE or FALSE, based on success.
  */
-function imageapi_image_scale_and_crop($image, $width, $height) {
+function imageapi_image_scale_and_crop(&$image, $width, $height) {
   $scale = max($width / $image->info['width'], $height / $image->info['height']);
   $x = ($image->info['width'] * $scale - $width) / 2;
   $y = ($image->info['height'] * $scale - $height) / 2;