diff --git a/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js b/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
index fd7243ed95..43bbfcaf09 100644
--- a/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
+++ b/django/contrib/admin/static/admin/js/admin/DateTimeShortcuts.js
@@ -21,7 +21,7 @@
         init: function() {
             var body = document.getElementsByTagName('body')[0];
             var serverOffset = body.getAttribute('data-admin-utc-offset');
-            if (serverOffset !== undefined) {
+            if (serverOffset) {
                 var localOffset = new Date().getTimezoneOffset() * -60;
                 DateTimeShortcuts.timezoneOffset = localOffset - serverOffset;
             }
@@ -43,7 +43,7 @@
         now: function() {
             var body = document.getElementsByTagName('body')[0];
             var serverOffset = body.getAttribute('data-admin-utc-offset');
-            if (serverOffset !== undefined) {
+            if (serverOffset) {
                 var localNow = new Date();
                 var localOffset = localNow.getTimezoneOffset() * -60;
                 localNow.setTime(localNow.getTime() + 1000 * (serverOffset - localOffset));
diff --git a/docs/releases/1.9.1.txt b/docs/releases/1.9.1.txt
index 20fd723d2b..2e1aa7cbb1 100644
--- a/docs/releases/1.9.1.txt
+++ b/docs/releases/1.9.1.txt
@@ -46,3 +46,7 @@ Bugfixes
 
 * Fixed ``TypedChoiceField`` change detection with nullable fields
   (:ticket:`25942`).
+
+* Fixed incorrect timezone warnings in custom admin templates that don't have
+  a ``data-admin-utc-offset`` attribute in the ``body`` tag.
+  (:ticket:`25845`).
diff --git a/js_tests/admin/DateTimeShortcuts.test.js b/js_tests/admin/DateTimeShortcuts.test.js
index 2fc9d9a8c6..e993090233 100644
--- a/js_tests/admin/DateTimeShortcuts.test.js
+++ b/js_tests/admin/DateTimeShortcuts.test.js
@@ -16,4 +16,8 @@ test('init', function(assert) {
     assert.equal(shortcuts.length, 1);
     assert.equal(shortcuts.find('a:first').text(), 'Today');
     assert.equal(shortcuts.find('a:last .date-icon').length, 1);
+
+    // To prevent incorrect timezone warnings on date/time widgets, timezoneOffset
+    // should be 0 when a timezone offset isn't set in the HTML body attribute.
+    assert.equal(DateTimeShortcuts.timezoneOffset, 0);
 });