diff --git a/CHANGELOG b/CHANGELOG
index 2f86a5bfb79..b03c7376470 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -93,6 +93,7 @@ CHANGELOG Roundcube Webmail
 - Fix bug where some forbidden characters on Cyrus-IMAP were not prevented from use in folder names
 - Fix bug where only attachments with the same name would be ignored on zip download (#6301)
 - Fix bug where unicode contact names could have been broken/emptied or caused DB errors (#6299)
+- Fix bug where after "mark all folders as read" action message counters were not reset (#6307)
 
 RELEASE 1.3.6
 -------------
diff --git a/program/lib/Roundcube/rcube_imap.php b/program/lib/Roundcube/rcube_imap.php
index 6f740003a9f..17a501695f2 100644
--- a/program/lib/Roundcube/rcube_imap.php
+++ b/program/lib/Roundcube/rcube_imap.php
@@ -2463,7 +2463,7 @@ public function print_raw_body($uid, $formatted = true)
      * @param string  $folder     Folder name
      * @param boolean $skip_cache True to skip message cache clean up
      *
-     * @return boolean  Operation status
+     * @return boolean Operation status
      */
     public function set_flag($uids, $flag, $folder=null, $skip_cache=false)
     {
diff --git a/program/steps/mail/check_recent.inc b/program/steps/mail/check_recent.inc
index 984c53c41cc..ac0f360ebd0 100644
--- a/program/steps/mail/check_recent.inc
+++ b/program/steps/mail/check_recent.inc
@@ -71,8 +71,7 @@ foreach ($a_mailboxes as $mbox_name) {
             array('mailbox' => $mbox_name, 'is_current' => $is_current, 'diff' => $diff));
     }
 
-    rcmail_send_unread_count($mbox_name, true, null,
-      (!$is_current && ($status & 1)) ? 'recent' : '');
+    rcmail_send_unread_count($mbox_name, true, null, (!$is_current && ($status & 1)) ? 'recent' : '');
 
     if ($status && $is_current) {
         // refresh saved search set
diff --git a/program/steps/mail/func.inc b/program/steps/mail/func.inc
index 0ab2dba0f2c..3a6863817c0 100644
--- a/program/steps/mail/func.inc
+++ b/program/steps/mail/func.inc
@@ -756,7 +756,7 @@ function rcmail_send_unread_count($mbox_name, $force=false, $count=null, $mark='
         $unseen = $RCMAIL->storage->count($mbox_name, 'UNSEEN', $force);
     }
 
-    if ($unseen != $old_unseen || ($mbox_name == 'INBOX')) {
+    if ($unseen !== $old_unseen || ($mbox_name == 'INBOX')) {
         $RCMAIL->output->command('set_unread_count', $mbox_name, $unseen,
             ($mbox_name == 'INBOX'), $unseen && $mark ? $mark : '');
     }
diff --git a/program/steps/mail/mark.inc b/program/steps/mail/mark.inc
index 1cb8091a2c8..eb5e416f471 100644
--- a/program/steps/mail/mark.inc
+++ b/program/steps/mail/mark.inc
@@ -70,7 +70,7 @@ if ($_uids && $flag) {
 
     foreach ($input as $mbox => $uids) {
         $marked += (int)$RCMAIL->storage->set_flag($uids, $flag, $mbox);
-        $count += count($uids);
+        $count  += is_array($uids) ? count($uids) : 1;
     }
 
     if (!$marked) {