diff --git a/Bugzilla/Bug.pm b/Bugzilla/Bug.pm
index f4f1069d26..36c4e53572 100644
--- a/Bugzilla/Bug.pm
+++ b/Bugzilla/Bug.pm
@@ -4636,14 +4636,14 @@ sub GetBugActivity {
         foreach my $value (split /, /, $removed) {
           if (substr($value, 0, length $url_base) eq $url_base) {
             my ($bug_id) = $value =~ /id=(\d+)$/;
-            next if !Bugzilla->user->can_see_bug($bug_id);
+            next if !$bug_id || !Bugzilla->user->can_see_bug($bug_id);
           }
           push @filtered_removed, $value;
         }
         foreach my $value (split /, /, $added) {
           if (substr($value, 0, length $url_base) eq $url_base) {
             my ($bug_id) = $value =~ /id=(\d+)$/;
-            next if !Bugzilla->user->can_see_bug($bug_id);
+            next if !$bug_id || !Bugzilla->user->can_see_bug($bug_id);
           }
           push @filtered_added, $value;
         }
diff --git a/Bugzilla/BugUrl/Bugzilla/Local.pm b/Bugzilla/BugUrl/Bugzilla/Local.pm
index 8ae5d3ff26..c358027389 100644
--- a/Bugzilla/BugUrl/Bugzilla/Local.pm
+++ b/Bugzilla/BugUrl/Bugzilla/Local.pm
@@ -13,6 +13,7 @@ use warnings;
 
 use base qw(Bugzilla::BugUrl::Bugzilla);
 
+use Bugzilla::Bug qw(bug_alias_to_id);
 use Bugzilla::Error;
 use Bugzilla::Util;
 
@@ -73,7 +74,19 @@ sub _check_value {
     $uri = $class->SUPER::_check_value($uri);
   }
 
-  my $ref_bug_id  = $uri->query_param('id');
+  # If bug ID is an alias, we want to store the value in the DB
+  # as the actual ID instead of the alias for visibility checking
+  # and other parts of the code.
+  my $ref_bug_id = $uri->query_param('id');
+  if ($ref_bug_id !~ /^\d+$/) {
+    my $orig_ref_bug_id = $ref_bug_id;
+    $ref_bug_id = bug_alias_to_id($ref_bug_id);
+    $ref_bug_id
+      || ThrowUserError('improper_bug_id_field_value',
+      {bug_id => $orig_ref_bug_id});
+    $uri->query_param('id', $ref_bug_id);
+  }
+
   my $ref_bug     = Bugzilla::Bug->check($ref_bug_id);
   my $self_bug_id = $params->{bug_id};
   $params->{ref_bug} = $ref_bug;