diff --git a/flickr.inc b/flickr.inc
index 76bc9d4..bb7e684 100644
--- a/flickr.inc
+++ b/flickr.inc
@@ -269,7 +269,7 @@ function flickr_photo_img($photo, $size = NULL, $format = NULL) {
   $id = isset($photo['primary']) ? $photo['primary'] : $photo['id'];
   $secret = $photo['secret'];
 
-  return "http://farm{$farm}.static.flickr.com/{$server}/{$id}_{$secret}" . ($size ? "_$size." : '.') . ($size == 'o' ? $format : 'jpg');
+  return "//farm{$farm}.static.flickr.com/{$server}/{$id}_{$secret}" . ($size ? "_$size." : '.') . ($size == 'o' ? $format : 'jpg');
 }
 
 /**