diff --git a/lib/redmine/database.rb b/lib/redmine/database.rb
index 0f0876157..bbc90c810 100644
--- a/lib/redmine/database.rb
+++ b/lib/redmine/database.rb
@@ -69,21 +69,16 @@ module Redmine
       # Returns a SQL statement to cast a timestamp column to a date given a time zone
       # Returns nil if not implemented for the current database
       def timestamp_to_date(column, time_zone)
+        return nil unless postgresql? || mysql?
+        # param:time_zone or config.time_zone
+        identifier = ActiveSupport::TimeZone.find_tzinfo((time_zone || Time.zone).name).identifier
+
         if postgresql?
-          if time_zone
-            identifier = ActiveSupport::TimeZone.find_tzinfo(time_zone.name).identifier
-            "(#{column}::timestamptz AT TIME ZONE '#{identifier}')::date"
-          else
-            "#{column}::date"
-          end
-        elsif mysql?
-          if time_zone
-            user_identifier = ActiveSupport::TimeZone.find_tzinfo(time_zone.name).identifier
-            local_identifier = ActiveSupport::TimeZone.find_tzinfo(Time.zone.name).identifier
-            "DATE(CONVERT_TZ(#{column},'#{local_identifier}', '#{user_identifier}'))"
-          else
-            "DATE(#{column})"
-          end
+          "(#{column}::timestamptz AT TIME ZONE '#{identifier}')::date"
+        else
+          # MySQL:
+          # convert from local time zone to tz
+          "DATE(CONVERT_TZ(#{column}, @@session.time_zone, '#{identifier}'))"
         end
       end
 
diff --git a/test/functional/issues_controller_test.rb b/test/functional/issues_controller_test.rb
index 50ba64a88..87d53ee8b 100644
--- a/test/functional/issues_controller_test.rb
+++ b/test/functional/issues_controller_test.rb
@@ -443,9 +443,8 @@ class IssuesControllerTest < Redmine::ControllerTest
       }
     )
     assert_response :success
-
     # group_name depends on localtime
-    group_name = format_date(Issue.second.created_on.localtime)
+    group_name = format_date(User.current.time_to_date(Issue.second.created_on))
     assert_select 'tr.group span.name', :text => group_name do
       assert_select '+ span.count', :text => '2'
     end