diff --git a/modules/node/node.install b/modules/node/node.install
index 16d3dba..43bfd53 100644
--- a/modules/node/node.install
+++ b/modules/node/node.install
@@ -914,6 +914,7 @@ function node_update_7012() {
  * Change {node}.vid default value from 0 to NULL to avoid deadlock issues on MySQL.
  */
 function node_update_7013() {
+  db_drop_unique_key('node', 'vid');
   db_change_field('node', 'vid', 'vid', array(
     'description' => 'The current {node_revision}.vid version identifier.',
     'type' => 'int',
@@ -921,6 +922,7 @@ function node_update_7013() {
     'not null' => FALSE,
     'default' => NULL,
   ));
+  db_add_unique_key('node', 'vid', array('vid'));
 }
 
 /**
diff --git a/modules/system/system.install b/modules/system/system.install
index 7b66767..338e73a 100644
--- a/modules/system/system.install
+++ b/modules/system/system.install
@@ -3032,6 +3032,7 @@ function system_update_7073() {
     'default' => '',
     'binary' => TRUE,
   ));
+  db_drop_unique_key('file_managed', 'uri');
   db_change_field('file_managed', 'uri', 'uri', array(
     'description' => 'The URI to access the file (either local or remote).',
     'type' => 'varchar',
@@ -3040,6 +3041,7 @@ function system_update_7073() {
     'default' => '',
     'binary' => TRUE,
   ));
+  db_add_unique_key('file_managed', 'uri', array('uri'));
 }
 
 /**