diff --git a/docs/changelog/7.x.x.txt b/docs/changelog/7.x.x.txt
index de4bda692..15d450fcb 100644
--- a/docs/changelog/7.x.x.txt
+++ b/docs/changelog/7.x.x.txt
@@ -1,4 +1,5 @@
 7.7.18
+ - fixed #10789: Inbox message states not deleted when a user is deleted
  - fixed #10739: Textarea and Codearea resize don't work in IE or Webkit browsers
  - fixed #10552: Map: Editing map properties resets zoom level to 0
  - fixed #10758: CS #replies does not get updated after post restore from trash (Bart Jol / Procolix)
diff --git a/docs/upgrades/upgrade_7.7.17-7.7.18.pl b/docs/upgrades/upgrade_7.7.17-7.7.18.pl
index 52220794a..55b53b5e8 100644
--- a/docs/upgrades/upgrade_7.7.17-7.7.18.pl
+++ b/docs/upgrades/upgrade_7.7.17-7.7.18.pl
@@ -34,6 +34,7 @@ my $session = start(); # this line required
 addSmsGatewaySubjectSetting($session);
 addInboxNotificationsSubjectSetting($session);
 profileFieldRequiredEditable($session);
+deleteOldInboxMessageStates($session);
 finish($session); # this line required
 
 #----------------------------------------------------------------------------
@@ -45,6 +46,15 @@ finish($session); # this line required
 #    print "DONE!\n" unless $quiet;
 #}
 
+sub deleteOldInboxMessageStates {
+    my $session = shift;
+    print "\tDelete Inbox messages states for users who have been deleted... " unless $quiet;
+    $session->db->write(<<EOSQL);
+DELETE FROM inbox_messageState WHERE userId NOT IN (SELECT userId FROM users)
+EOSQL
+    print "DONE!\n" unless $quiet;
+}
+
 sub profileFieldRequiredEditable {
     my $session = shift;
     print "\tTurn on the editable bit for all Profile Fields which are required... " unless $quiet;