diff --git a/lib/db/install.xml b/lib/db/install.xml
index 9a0f927097c..de8750aa922 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -569,6 +569,7 @@
       <INDEXES>
         <INDEX NAME="useridto" UNIQUE="false" FIELDS="useridto"/>
         <INDEX NAME="useridfromtodeleted" UNIQUE="false" FIELDS="useridfrom, useridto, timeuserfromdeleted, timeusertodeleted"/>
+        <INDEX NAME="notificationtimeread" UNIQUE="false" FIELDS="notification, timeread"/>
       </INDEXES>
     </TABLE>
     <TABLE NAME="message_contacts" COMMENT="Maintains lists of relationships between users">
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 56e153f0639..4fd7aeae008 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -4584,5 +4584,20 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2015092900.00);
     }
 
+    if ($oldversion < 2015100600.00) {
+
+        // Define index notification (not unique) to be added to message_read.
+        $table = new xmldb_table('message_read');
+        $index = new xmldb_index('notificationtimeread', XMLDB_INDEX_NOTUNIQUE, array('notification', 'timeread'));
+
+        // Conditionally launch add index notification.
+        if (!$dbman->index_exists($table, $index)) {
+            $dbman->add_index($table, $index);
+        }
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2015100600.00);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 4732f168d81..1f58f2433a6 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2015100200.00;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2015100600.00;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.