diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 98f30a7..dd4bd6a 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2261,10 +2261,10 @@ function theme_table($variables) {
           $i++;
 
           if (!is_array($cell)) {
-            $cell = array('data' => $cell, 'attributes' => new Attribute(array('class' => array())));
+            $cell = array('data' => $cell, 'attributes' => new Attribute());
             // Add responsive class.
             if (isset($responsive[$i])) {
-              $cell['attributes']['class'][] = $responsive[$i];
+              $cell['attributes']['class'] = array($responsive[$i]);
             }
           }
           else {