diff --git a/core/includes/common.inc b/core/includes/common.inc
index 0dbabd8484e3155e04ff8ef5b5b28f78f2c32bdb..eb7362cb473c603e8878fb13142d6df9a0238714 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -3916,7 +3916,7 @@ function drupal_render(&$elements) {
       // only this theme() call. This allows #theme hooks and #theme_wrappers
       // hooks to share variable names without conflict or ambiguity.
       $wrapper_elements = $elements;
-      if (is_array($value)) {
+      if (is_string($key)) {
         $wrapper_hook = $key;
         foreach ($value as $attribute => $override) {
           $wrapper_elements[$attribute] = $override;
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/RenderTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/RenderTest.php
index 17993432ad4437511c25a7fcf2ae071667a9b79d..be4d7e533f030e900bbbf0ae5006fc5a295e1729 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/RenderTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/RenderTest.php
@@ -134,6 +134,15 @@ function testDrupalRenderBasics() {
         ),
         'expected' => '<div class="foo"><div class="bar"></div></div>',
       ),
+      // Array syntax theme hook suggestion in #theme_wrappers.
+      array(
+        'name' => '#theme_wrappers implements an array style theme hook suggestion',
+        'value' => array(
+          '#theme_wrappers' => array(array('container')),
+          '#attributes' => array('class' => 'foo'),
+        ),
+        'expected' => '<div class="foo"></div>',
+      ),
 
       // Test handling of #markup as a fallback for #theme hooks.
       // Simple #markup with no theme.