diff --git a/mozilla/webtools/bugzilla/Bugzilla/Util.pm b/mozilla/webtools/bugzilla/Bugzilla/Util.pm
index 2c45e077f4d..70b4c68457d 100644
--- a/mozilla/webtools/bugzilla/Bugzilla/Util.pm
+++ b/mozilla/webtools/bugzilla/Bugzilla/Util.pm
@@ -30,6 +30,7 @@ use strict;
 
 use base qw(Exporter);
 @Bugzilla::Util::EXPORT = qw(is_tainted trick_taint detaint_natural
+                             detaint_signed
                              html_quote url_quote value_quote xml_quote
                              css_class_quote
                              lsearch max min
@@ -69,6 +70,16 @@ sub detaint_natural {
     return (defined($_[0]));
 }
 
+sub detaint_signed {
+    $_[0] =~ /^([-+]?\d+)$/;
+    $_[0] = $1;
+    # Remove any leading plus sign.
+    if (defined($_[0]) && $_[0] =~ /^\+(\d+)$/) {
+        $_[0] = $1;
+    }
+    return (defined($_[0]));
+}
+
 sub html_quote {
     my ($var) = (@_);
     $var =~ s/\&/\&/g;
@@ -325,6 +336,7 @@ Bugzilla::Util - Generic utility functions for bugzilla
   $rv = is_tainted($var);
   trick_taint($var);
   detaint_natural($var);
+  detaint_signed($var);
 
   # Functions for quoting
   html_quote($var);
@@ -393,6 +405,12 @@ This routine detaints a natural number. It returns a true value if the
 value passed in was a valid natural number, else it returns false. You
 B<MUST> check the result of this routine to avoid security holes.
 
+=item C<detaint_signed($num)>
+
+This routine detaints a signed integer. It returns a true value if the
+value passed in was a valid signed integer, else it returns false. You
+B<MUST> check the result of this routine to avoid security holes.
+
 =back
 
 =head2 Quoting
diff --git a/mozilla/webtools/bugzilla/docs/xml/administration.xml b/mozilla/webtools/bugzilla/docs/xml/administration.xml
index f0ccf027e9a..e8d70a10282 100644
--- a/mozilla/webtools/bugzilla/docs/xml/administration.xml
+++ b/mozilla/webtools/bugzilla/docs/xml/administration.xml
@@ -672,7 +672,7 @@
       <listitem>
         <para>Enter the name of the Milestone in the "Milestone" field. You
         can optionally set the "sortkey", which is a positive or negative
-        number (-255 to 255) that defines where in the list this particular
+        number (-32768 to 32767) that defines where in the list this particular
         milestone appears. This is because milestones often do not 
         occur in alphanumeric order For example, "Future" might be
         after "Release 1.2". Select "Add".</para>
diff --git a/mozilla/webtools/bugzilla/editmilestones.cgi b/mozilla/webtools/bugzilla/editmilestones.cgi
index 5c9e214689d..32e6790c267 100755
--- a/mozilla/webtools/bugzilla/editmilestones.cgi
+++ b/mozilla/webtools/bugzilla/editmilestones.cgi
@@ -116,6 +116,21 @@ sub CheckMilestone ($$)
     }
 }
 
+sub CheckSortkey ($$)
+{
+    my ($milestone, $sortkey) = @_;
+    # Keep a copy in case detaint_signed() clears the sortkey
+    my $stored_sortkey = $sortkey;
+
+    if (!detaint_signed($sortkey) || $sortkey < -32768 || $sortkey > 32767) {
+        ThrowUserError('milestone_sortkey_invalid',
+                       {'name' => $milestone,
+                        'sortkey' => $stored_sortkey});
+    }
+
+    return $sortkey;
+}
+
 #
 # Preliminary checks:
 #
@@ -261,13 +276,8 @@ if ($action eq 'new') {
                        {'name' => $milestone});
     }
 
-    # Need to store in case detaint_natural() clears the sortkey
-    my $stored_sortkey = $sortkey;
-    if (!detaint_natural($sortkey)) {
-        ThrowUserError('milestone_sortkey_invalid',
-                       {'name' => $milestone,
-                        'sortkey' => $stored_sortkey});
-    }
+    $sortkey = CheckSortkey($milestone, $sortkey);
+
     if (TestMilestone($product, $milestone)) {
         ThrowUserError('milestone_already_exists',
                        {'name' => $milestone,
@@ -453,15 +463,8 @@ if ($action eq 'update') {
                          'milestones WRITE',
                          'products WRITE');
 
-    # Need to store because detaint_natural() will delete this if
-    # invalid
-    my $stored_sortkey = $sortkey;
-    if ($sortkey != $sortkeyold) {
-        if (!detaint_natural($sortkey)) {
-            ThrowUserError('milestone_sortkey_invalid',
-                           {'name' => $milestone,
-                            'sortkey' => $stored_sortkey});
-        }
+    if ($sortkey ne $sortkeyold) {
+        $sortkey = CheckSortkey($milestone, $sortkey);
 
         trick_taint($milestoneold);
 
diff --git a/mozilla/webtools/bugzilla/template/en/default/global/user-error.html.tmpl b/mozilla/webtools/bugzilla/template/en/default/global/user-error.html.tmpl
index 6c1af5b26cd..b7cefa9a314 100644
--- a/mozilla/webtools/bugzilla/template/en/default/global/user-error.html.tmpl
+++ b/mozilla/webtools/bugzilla/template/en/default/global/user-error.html.tmpl
@@ -720,7 +720,8 @@
   [% ELSIF error == "milestone_sortkey_invalid" %]
     [% title = "Invalid Milestone Sortkey" %]
     The sortkey '[% sortkey FILTER html %]' for milestone '
-    [% name FILTER html %]' is not a valid (positive) number.
+    [% name FILTER html %]' is not in the range -32768 &le; sortkey
+    &le; 32767.
 
   [% ELSIF error == "misarranged_dates" %]
     [% title = "Misarranged Dates" %]