diff --git a/lib/groupdate/magic.rb b/lib/groupdate/magic.rb
index 840a602..e2f5018 100644
--- a/lib/groupdate/magic.rb
+++ b/lib/groupdate/magic.rb
@@ -87,8 +87,11 @@ module Groupdate
           raise "Connection adapter not supported: #{adapter_name}"
         end
 
-      group = relation.group(Groupdate::OrderHack.new(relation.send(:sanitize_sql_array, query), field, time_zone))
-      if options[:series] == false
+      group_query = relation.send(:sanitize_sql_array, query)
+      group = relation.group(Groupdate::OrderHack.new(group_query, field, time_zone))
+      if options[:select]
+        group.select(options[:select] + ", #{group_query} AS #{field}")
+      elsif options[:series] == false
         group
       else
         relation =
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 6120a1d..7d1c686 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -772,6 +772,17 @@ module TestGroupdate
     assert_equal expected, User.group_by_day(:created_at, time_zone: "Brasilia").count
   end
 
+  # select
+
+  def test_select
+    create_user("2014-10-19 00:00:00")
+    create_user("2014-10-19 00:00:00", 2)
+    result = User.group_by_day(:created_at, select: "COUNT(*) AS count, SUM(score) AS sum").to_a.first
+    assert_equal 2, result.count
+    assert_equal 3, result.sum
+    assert_equal utc.parse("2014-10-19 00:00:00"), result.day
+  end
+
   # helpers
 
   def assert_format(method, expected, format, options = {})
--
libgit2 0.21.0