diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index 1f52076f3d2..8e893702e98 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -1183,6 +1183,10 @@ set time_zone= @@global.time_zone;
 select str_to_date('10:00 PM', '%h:%i %p') + INTERVAL 10 MINUTE;
 str_to_date('10:00 PM', '%h:%i %p') + INTERVAL 10 MINUTE
 NULL
+SELECT TIME_FORMAT(SEC_TO_TIME(a),"%H:%i:%s") FROM (SELECT 3020399 AS a UNION SELECT 3020398 ) x GROUP BY 1;
+TIME_FORMAT(SEC_TO_TIME(a),"%H:%i:%s")
+838:59:58
+838:59:59
 End of 5.0 tests
 select date_sub("0050-01-01 00:00:01",INTERVAL 2 SECOND);
 date_sub("0050-01-01 00:00:01",INTERVAL 2 SECOND)
diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index ebaa6d84bd3..aacb4db940f 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -692,6 +692,14 @@ set time_zone= @@global.time_zone;
 #
 
 select str_to_date('10:00 PM', '%h:%i %p') + INTERVAL 10 MINUTE;
+
+
+#
+# Bug #20293: group by cuts off value from time_format
+#
+# Check if using GROUP BY with TIME_FORMAT() produces correct results
+
+SELECT TIME_FORMAT(SEC_TO_TIME(a),"%H:%i:%s") FROM (SELECT 3020399 AS a UNION SELECT 3020398 ) x GROUP BY 1;
 --echo End of 5.0 tests
 
 #