diff --git a/src/Render/AmpResponseAttachmentsProcessor.php b/src/Render/AmpResponseAttachmentsProcessor.php
index dd3b622..9f2d79f 100644
--- a/src/Render/AmpResponseAttachmentsProcessor.php
+++ b/src/Render/AmpResponseAttachmentsProcessor.php
@@ -232,7 +232,7 @@ class AmpResponseAttachmentsProcessor implements AmpAttachmentsResponseProcessor
     $schema_metatags = [];
     foreach ($amp_html_head as $item) {
       list($data, $key) = $item;
-      if ($data['#attributes']['schema_metatag']) {
+      if (array_key_exists('schema_metatag', $data['#attributes'])) {
         // Schema metatag: First time through, collect and nest by group.
         $group = $data['#attributes']['group'];
         // Nest items by the group they are in.
@@ -244,7 +244,7 @@ class AmpResponseAttachmentsProcessor implements AmpAttachmentsResponseProcessor
         continue;
       }
 
-      if ($data['#attributes']['rel'] == 'canonical') {
+      if (array_key_exists('rel', $data['#attributes']) && $data['#attributes']['rel'] == 'canonical') {
         continue;
       }
 
@@ -277,7 +277,6 @@ class AmpResponseAttachmentsProcessor implements AmpAttachmentsResponseProcessor
             '#value' => $jsonld,
             '#attributes' => ['type' => 'application/ld+json'],
           ],
-          'schema_metatag',
         ];
       }
     }