diff --git a/backup/cc/entities.class.php b/backup/cc/entities.class.php
index e0737fdca11..368c7e0ea6d 100644
--- a/backup/cc/entities.class.php
+++ b/backup/cc/entities.class.php
@@ -309,7 +309,6 @@ class entities {
             $source = str_split($source, 1);
 
             for ($i = 1; $i <= $length; $i++) {
-                mt_srand((double) microtime() * 1000000);
                 $num = mt_rand(1, count($source));
                 $response .= $source[$num - 1];
             }
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 7ec54c804d0..a0d3bd352c3 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -9393,7 +9393,6 @@ function random_string ($length=15) {
     $pool .= 'abcdefghijklmnopqrstuvwxyz';
     $pool .= '0123456789';
     $poollen = strlen($pool);
-    mt_srand ((double) microtime() * 1000000);
     $string = '';
     for ($i = 0; $i < $length; $i++) {
         $string .= substr($pool, (mt_rand()%($poollen)), 1);
@@ -9414,7 +9413,6 @@ function complex_random_string($length=null) {
     $pool  = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
     $pool .= '`~!@#%^&*()_+-=[];,./<>?:{} ';
     $poollen = strlen($pool);
-    mt_srand ((double) microtime() * 1000000);
     if ($length===null) {
         $length = floor(rand(24,32));
     }