diff -u b/modules/field/field.api.php b/modules/field/field.api.php
--- b/modules/field/field.api.php
+++ b/modules/field/field.api.php
@@ -281,9 +281,9 @@
 /**
  * Allow modules to alter the schema for a field.
  *
- * @param $schema
+ * @param array $schema
  *   The schema definition as returned by hook_field_schema().
- * @param $field
+ * @param array $field
  *   The field definition.
  *
  * @see field_retrieve_schema()
diff -u b/modules/field/field.crud.inc b/modules/field/field.crud.inc
--- b/modules/field/field.crud.inc
+++ b/modules/field/field.crud.inc
@@ -23,13 +23,15 @@
 /**
  * Retrieves the schema for a field.
  *
- * @param $field
+ * @param array $field
  *   The field array to get the schema definition against.
- * @return
+ * @return array
  *   The field schema definition array.
  */
 function field_retrieve_schema($field) {
-  module_load_install($field['module']);
+  // Make sure the installation API is available.
+  include_once DRUPAL_ROOT . '/includes/install.inc';
+  module_load_all_includes('install');
   $schema = (array) module_invoke($field['module'], 'field_schema', $field);
   $schema += array('columns' => array(), 'indexes' => array(), 'foreign keys' => array());
   // Give other modules a chance to alter this definition.
diff -u b/modules/field/tests/field_test_schema_alter.module b/modules/field/tests/field_test_schema_alter.module
--- b/modules/field/tests/field_test_schema_alter.module
+++ b/modules/field/tests/field_test_schema_alter.module
@@ -2,22 +1,0 @@
-
-/**
- * @file
- * Helper module for the Field API schema alter tests.
- */
-
-/**
- * Implements hook_field_schema_alter().
- */
-function field_test_schema_alter_field_schema_alter(&$schema, $field) {
-  if ($field['type'] == 'test_field') {
-    // Alter the field type.
-    $schema['columns']['value']['type'] = 'float';
-    // Add an additional column of data.
-    $schema['columns']['additional_column'] = array(
-      'description' => "Additional column added to image field table.",
-      'type' => 'varchar',
-      'length' => 128,
-      'not null' => FALSE,
-    );
-  }
-}
only in patch2:
unchanged:
--- /dev/null
+++ b/modules/field/tests/field_test_schema_alter.install
@@ -0,0 +1,23 @@
+<?php
+
+/**
+ * @file
+ * Install, update and uninstall functions for the field_test_schema_alter module.
+ */
+
+/**
+ * Implements hook_field_schema_alter().
+ */
+function field_test_schema_alter_field_schema_alter(&$schema, $field) {
+  if ($field['type'] == 'test_field') {
+    // Alter the field type.
+    $schema['columns']['value']['type'] = 'float';
+    // Add an additional column of data.
+    $schema['columns']['additional_column'] = array(
+      'description' => "Additional column added to image field table.",
+      'type' => 'varchar',
+      'length' => 128,
+      'not null' => FALSE,
+    );
+  }
+}