diff --git a/picture.module b/picture.module
index aba547a..8d3a6f4 100644
--- a/picture.module
+++ b/picture.module
@@ -1585,7 +1585,7 @@ function theme_image_srcset(array $variables) {
     $attributes['srcset'] = implode(', ', $srcsets);
   }
   foreach (array('width', 'height', 'alt', 'title', 'sizes') as $key) {
-    if (isset($variables[$key])) {
+    if (!empty($variables[$key])) {
       $attributes[$key] = $variables[$key];
     }
   }