diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index c6f3bc47d..524939508 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -13,6 +13,7 @@ Bug Fixes::
 * Invoke `LoggerManager#setLogger` setter - thanks @mojavelinux (#1322)
 * Strip alternate BOM that uses char code 65279 when input passes through a Buffer - thanks @mojavelinux (#1344)
 * Properly cache the helpers file in the template converter - thanks @yGuy (#1373)
+* Fix global variable leak (#1493)
 
 Improvements::
 
diff --git a/packages/core/lib/asciidoctor/js/asciidoctor_ext/document.rb b/packages/core/lib/asciidoctor/js/asciidoctor_ext/document.rb
index 72fa9ab33..d5c06194d 100644
--- a/packages/core/lib/asciidoctor/js/asciidoctor_ext/document.rb
+++ b/packages/core/lib/asciidoctor/js/asciidoctor_ext/document.rb
@@ -8,6 +8,12 @@ def fill_datetime_attributes attrs, input_mtime
       var nil = Opal.nil
       var utc_offset
       var source_date_epoch
+      var localdate
+      var localyear
+      var localtime
+      var localdatetime
+      var docdate
+      var doctime
 
       var getYear = function (time, utc_offset) {
         return utc_offset === 0 ? time.getUTCFullYear() : time.getFullYear()
@@ -95,6 +101,7 @@ def fill_datetime_attributes attrs, input_mtime
         var mtime_hours = ('0' + (getHours(input_mtime, utc_offset))).slice(-2)
         var mtime_minutes = ('0' + (input_mtime.getMinutes())).slice(-2)
         var mtime_seconds = ('0' + (input_mtime.getSeconds())).slice(-2)
+        var utc_offset_format
         if (utc_offset === 0) {
           utc_offset_format = 'UTC'
         } else if (utc_offset > 0) {
diff --git a/packages/core/spec/node/asciidoctor.spec.js b/packages/core/spec/node/asciidoctor.spec.js
index 61980c896..9548837b4 100644
--- a/packages/core/spec/node/asciidoctor.spec.js
+++ b/packages/core/spec/node/asciidoctor.spec.js
@@ -520,6 +520,7 @@ intro
     it('should be able to load a file', () => {
       const doc = asciidoctor.loadFile(resolveFixture('test.adoc'))
       expect(doc.getAttribute('docname')).to.equal('test')
+      expect(global.localdatetime).to.be.undefined()
     })
 
     it('should be able to load a buffer', () => {