diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index 164c3d610b6..16a1e5d01d7 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -1218,6 +1218,10 @@ t1	t2	SEC_TO_TIME( TIME_TO_SEC( t2 ) - TIME_TO_SEC( t1 ) )	QUARTER(d)
 11:00:00	11:15:00	00:15:00	1
 10:00:00	NULL	NULL	NULL
 DROP TABLE t1;
+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 41f0899cc66..4b952b66ff3 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -724,6 +724,13 @@ SELECT t1, t2, SEC_TO_TIME( TIME_TO_SEC( t2 ) - TIME_TO_SEC( t1 ) ), QUARTER(d)
 SELECT t1, t2, SEC_TO_TIME( TIME_TO_SEC( t2 ) - TIME_TO_SEC( t1 ) ), QUARTER(d)
   FROM t1 ORDER BY a DESC;
 DROP TABLE t1;
+
+#
+# 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
 
 #