diff --git a/src/wp-admin/includes/schema.php b/src/wp-admin/includes/schema.php
index 4814a05d74..14304d01f0 100644
--- a/src/wp-admin/includes/schema.php
+++ b/src/wp-admin/includes/schema.php
@@ -272,6 +272,7 @@ CREATE TABLE $wpdb->sitemeta (
   KEY site_id (site_id)
 ) $charset_collate;
 CREATE TABLE $wpdb->signups (
+  signup_id bigint(20) NOT NULL auto_increment,
   domain varchar(200) NOT NULL default '',
   path varchar(100) NOT NULL default '',
   title longtext NOT NULL,
@@ -282,8 +283,11 @@ CREATE TABLE $wpdb->signups (
   active tinyint(1) NOT NULL default '0',
   activation_key varchar(50) NOT NULL default '',
   meta longtext,
+  PRIMARY KEY  (signup_id),
   KEY activation_key (activation_key),
-  KEY domain (domain)
+  KEY user_email (user_email)
+  KEY user_login_email (user_login,user_email),
+  KEY domain_path (domain,path),
 ) $charset_collate;";
 
 	switch ( $scope ) {
diff --git a/src/wp-admin/includes/upgrade.php b/src/wp-admin/includes/upgrade.php
index 0d17d8fce4..63a6559561 100644
--- a/src/wp-admin/includes/upgrade.php
+++ b/src/wp-admin/includes/upgrade.php
@@ -1978,6 +1978,11 @@ function pre_schema_upgrade() {
 		$wpdb->query("ALTER TABLE $wpdb->options DROP INDEX option_name");
 	}
 
+	// Upgrade verions prior to 3.7
+	if ( $wp_current_db_version < 25179 && is_multisite() && is_main_network() && ! defined( 'DO_NOT_UPGRADE_GLOBAL_TABLES' ) ) {
+		$wpdb->query( "ALTER TABLE $wpdb->signups ADD signup_id BIGINT(20) NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST" );
+		$wpdb->query( "ALTER TABLE $wpdb->signups DROP INDEX domain" );
+	}
 }
 
 /**
diff --git a/src/wp-includes/version.php b/src/wp-includes/version.php
index f34a27ab00..4911bf2d6a 100644
--- a/src/wp-includes/version.php
+++ b/src/wp-includes/version.php
@@ -11,7 +11,7 @@ $wp_version = '3.7-alpha-25157';
  *
  * @global int $wp_db_version
  */
-$wp_db_version = 24448;
+$wp_db_version = 25179;
 
 /**
  * Holds the TinyMCE version