diff --git a/includes/microdata.form_alter.inc b/includes/microdata.form_alter.inc
index be7ce77..1f59539 100644
--- a/includes/microdata.form_alter.inc
+++ b/includes/microdata.form_alter.inc
@@ -240,47 +240,50 @@ function microdata_form_field_ui_field_edit_form_submit($form, &$form_state) {
   $values = $form_state['values'];
 
   $mapping = _microdata_load_mapping($entity_type, $bundle);
-  foreach ($values['microdata']['fields'] as $field_name => $field_values) {
-    $subfields = _microdata_get_field_properties($entity_type, $bundle, $field_name);
-    // If the field itself is microdata enabled, add the mapping for the field.
-    if (isset($field_values['field'])) {
-      $mapping[$field_name] = array(
-        '#itemprop' => drupal_explode_tags($field_values['field']['itemprop']),
-      );
 
-      // If the field should be handled as an item, add the is_item flag to the
-      // field's mapping and save the itemtype.
-      // @todo Consider adding the itemid.
-      if (!empty($field_values['field']['is_item'])) {
-        $mapping[$field_name]['#is_item'] = TRUE;
+  if (isset($values['microdata'])) {
+    foreach ($values['microdata']['fields'] as $field_name => $field_values) {
+      $subfields = _microdata_get_field_properties($entity_type, $bundle, $field_name);
+      // If the field itself is microdata enabled, add the mapping for the field.
+      if (isset($field_values['field'])) {
+        $mapping[$field_name] = array(
+          '#itemprop' => drupal_explode_tags($field_values['field']['itemprop']),
+        );
 
-        if (isset($field_values['field']['item_fieldset']['itemtype'])) {
-          $mapping[$field_name]['#itemtype'] = drupal_explode_tags($field_values['field']['item_fieldset']['itemtype']);
+        // If the field should be handled as an item, add the is_item flag to the
+        // field's mapping and save the itemtype.
+        // @todo Consider adding the itemid.
+        if (!empty($field_values['field']['is_item'])) {
+          $mapping[$field_name]['#is_item'] = TRUE;
+
+          if (isset($field_values['field']['item_fieldset']['itemtype'])) {
+            $mapping[$field_name]['#itemtype'] = drupal_explode_tags($field_values['field']['item_fieldset']['itemtype']);
+          }
+          else {
+            $mapping[$field_name]['#itemtype'] = array();
+          }
         }
         else {
-          $mapping[$field_name]['#itemtype'] = array();
+          $mapping[$field_name]['#is_item'] = FALSE;
         }
       }
-      else {
-        $mapping[$field_name]['#is_item'] = FALSE;
-      }
-    }
 
-    // Add the mappings for field properties.
-    foreach ($subfields as $subfield_name => $subfield) {
-      $element = array(
-        '#itemprop' => drupal_explode_tags($field_values['subfields'][$subfield_name]['itemprop']),
-      );
+      // Add the mappings for field properties.
+      foreach ($subfields as $subfield_name => $subfield) {
+        $element = array(
+          '#itemprop' => drupal_explode_tags($field_values['subfields'][$subfield_name]['itemprop']),
+        );
 
-      // If the subfield contains an item, save an itemtype scoped to this item.
-      // @todo Consider whether a subfield should ever be able to save an item.
-      if (isset($field_values[$subfield_name]['item_fieldset']['itemtype'])) {
-        $element['#itemtype'] = $field_values['subfields'][$subfield_name]['item_fieldset']['itemtype'];
-      }
-      else {
-        $element['#itemtype'] = '';
+        // If the subfield contains an item, save an itemtype scoped to this item.
+        // @todo Consider whether a subfield should ever be able to save an item.
+        if (isset($field_values[$subfield_name]['item_fieldset']['itemtype'])) {
+          $element['#itemtype'] = $field_values['subfields'][$subfield_name]['item_fieldset']['itemtype'];
+        }
+        else {
+          $element['#itemtype'] = '';
+        }
+        $mapping[$field_name][$subfield_name] = $element;
       }
-      $mapping[$field_name][$subfield_name] = $element;
     }
   }