diff --git a/test/integration/api_test/api_test.rb b/test/integration/api_test/api_test.rb
index 37affe934..b4ce92e53 100644
--- a/test/integration/api_test/api_test.rb
+++ b/test/integration/api_test/api_test.rb
@@ -40,12 +40,12 @@ class Redmine::ApiTest::ApiTest < Redmine::ApiTest::Base
 
   def test_json_datetime_format
     get '/users/1.json', :headers => credentials('admin')
-    assert_include '"created_on":"2006-07-19T17:12:21Z"', response.body
+    assert_include %Q["created_on":"#{Time.zone.parse('2006-07-19T17:12:21Z').iso8601}"], response.body
   end
 
   def test_xml_datetime_format
     get '/users/1.xml', :headers => credentials('admin')
-    assert_include '<created_on>2006-07-19T17:12:21Z</created_on>', response.body
+    assert_include "<created_on>#{Time.zone.parse('2006-07-19T17:12:21Z').iso8601}</created_on>", response.body
   end
 
   def test_head_response_should_have_empty_body
diff --git a/test/integration/api_test/issues_test.rb b/test/integration/api_test/issues_test.rb
index c5bf86744..516221801 100644
--- a/test/integration/api_test/issues_test.rb
+++ b/test/integration/api_test/issues_test.rb
@@ -211,10 +211,10 @@ class Redmine::ApiTest::IssuesTest < Redmine::ApiTest::Base
   test "GET /issues/:id.xml with journals should format timestamps in ISO 8601" do
     get '/issues/1.xml?include=journals'
 
-    iso_date = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$/
-    assert_select 'issue>created_on', :text => iso_date
-    assert_select 'issue>updated_on', :text => iso_date
-    assert_select 'issue journal>created_on', :text => iso_date
+    issue = Issue.find(1)
+    assert_select 'issue>created_on', :text => issue.created_on.iso8601
+    assert_select 'issue>updated_on', :text => issue.updated_on.iso8601
+    assert_select 'issue journal>created_on', :text => issue.journals[0].created_on.iso8601
   end
 
   test "GET /issues/:id.xml with custom fields" do