diff --git a/core/modules/block/block.install b/core/modules/block/block.install
index ec72d062edf6..3c1755f7614e 100644
--- a/core/modules/block/block.install
+++ b/core/modules/block/block.install
@@ -252,6 +252,34 @@ function block_update_8008() {
       'entity_types' => array('custom_block'),
       'module' => 'text',
       'cardinality' => 1,
+      'schema' => array(
+        'columns' => array(
+          'value' => array(
+            'type' => 'text',
+            'size' => 'big',
+            'not null' => FALSE,
+          ),
+          'summary' => array(
+            'type' => 'text',
+            'size' => 'big',
+            'not null' => FALSE,
+          ),
+          'format' => array(
+            'type' => 'varchar',
+            'length' => 255,
+            'not null' => FALSE,
+          ),
+        ),
+        'indexes' => array(
+          'format' => array('format'),
+        ),
+        'foreign keys' => array(
+          'format' => array(
+            'table' => 'filter_format',
+            'columns' => array('format' => 'format'),
+          ),
+        ),
+      ),
     );
     _update_8003_field_create_field($body_field);
 
diff --git a/core/modules/field/field.install b/core/modules/field/field.install
index b4251699eff9..c46346a097b6 100644
--- a/core/modules/field/field.install
+++ b/core/modules/field/field.install
@@ -15,7 +15,12 @@ use Drupal\field\Plugin\Core\Entity\Field;
  * they get executed after field_update_8003().
  *
  * @param array $field_config
- *   An array of field properties.
+ *   An array of field properties. Required properties are:
+ *   - 'id': The field id (machine name).
+ *   - 'type': The field type.
+ *   - 'module': The name of the module providing the field type.
+ *   - 'schema': The field schema, in the same format as
+ *     Drupal\field\Plugin\Type\FieldType\ConfigFieldInterface::schema().
  *
  * @ingroup update_api
  */
diff --git a/core/modules/field/lib/Drupal/field/Tests/CrudTest.php b/core/modules/field/lib/Drupal/field/Tests/CrudTest.php
index 8f3a995873c8..70c223606f3f 100644
--- a/core/modules/field/lib/Drupal/field/Tests/CrudTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/CrudTest.php
@@ -153,6 +153,24 @@ class CrudTest extends FieldUnitTestBase {
     }
   }
 
+  /**
+   * Tests that an explicit schema can be provided on creation of a field.
+   *
+   * This behavior is needed to allow field creation within updates, since
+   * plugin classes (and thus the field type schema) cannot be accessed.
+   */
+  function testCreateFieldWithExplicitSchema() {
+    $field_definition = array(
+      'field_name' => 'field_2',
+      'type' => 'test_field',
+      'schema' => array(
+        'dummy' => 'foobar'
+      ),
+    );
+    $field = entity_create('field_entity', $field_definition);
+    $this->assertEqual($field->getSchema(), $field_definition['schema']);
+  }
+
   /**
    * Test failure to create a field.
    */
diff --git a/core/modules/user/user.install b/core/modules/user/user.install
index 871c18d499a1..62eb4a93c1a0 100644
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -665,6 +665,47 @@ function user_update_8011() {
       'uri_scheme' => 'public',
       'default_image' => FALSE,
     ),
+    'schema' => array(
+      'columns' => array(
+        'target_id' => array(
+          'description' => 'The ID of the target entity.',
+          'type' => 'int',
+          'not null' => TRUE,
+          'unsigned' => TRUE,
+        ),
+        'alt' => array(
+          'description' => "Alternative image text, for the image's 'alt' attribute.",
+          'type' => 'varchar',
+          'length' => 512,
+          'not null' => FALSE,
+        ),
+        'title' => array(
+          'description' => "Image title text, for the image's 'title' attribute.",
+          'type' => 'varchar',
+          'length' => 1024,
+          'not null' => FALSE,
+        ),
+        'width' => array(
+          'description' => 'The width of the image in pixels.',
+          'type' => 'int',
+          'unsigned' => TRUE,
+        ),
+        'height' => array(
+          'description' => 'The height of the image in pixels.',
+          'type' => 'int',
+          'unsigned' => TRUE,
+        ),
+      ),
+      'indexes' => array(
+        'target_id' => array('target_id'),
+      ),
+      'foreign keys' => array(
+        'target_id' => array(
+          'table' => 'file_managed',
+          'columns' => array('target_id' => 'fid'),
+        ),
+      ),
+    ),
   );
   _update_8003_field_create_field($field);