diff --git a/core/modules/file/file.install b/core/modules/file/file.install
index 39d671c..87c5fb4 100644
--- a/core/modules/file/file.install
+++ b/core/modules/file/file.install
@@ -272,6 +272,7 @@ function file_update_8000() {
  * Convert the 'id' column in {file_usage} to accept UUIDs.
  */
 function file_update_8001() {
+  db_drop_primary_key('file_usage');
   $spec = array(
     'description' => 'The primary key of the object using the file.',
     'type' => 'varchar',
@@ -296,6 +297,7 @@ function file_update_8002() {
     );
     db_change_field('file_usage', 'module', 'module', $spec);
   }
+  db_add_primary_key('file_usage', array('fid', 'type', 'id', 'module'));
 }
 
 /**