diff --git a/mysql-test/r/func_gconcat.result b/mysql-test/r/func_gconcat.result
index b5bfadf1f57..04f83788571 100644
--- a/mysql-test/r/func_gconcat.result
+++ b/mysql-test/r/func_gconcat.result
@@ -937,4 +937,19 @@ SELECT GROUP_CONCAT(DISTINCT b, a ORDER BY b) FROM t1;
 GROUP_CONCAT(DISTINCT b, a ORDER BY b)
 11,22,32
 DROP TABLE t1, t2, t3;
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (),();
+SELECT s1.d1 FROM
+(
+SELECT
+t1.a as d1,
+GROUP_CONCAT(DISTINCT t1.a) AS d2
+FROM
+t1 AS t1,
+t1 AS t2
+GROUP BY 1
+) AS s1;
+d1
+NULL
+DROP TABLE t1;
 End of 5.0 tests
diff --git a/mysql-test/t/func_gconcat.test b/mysql-test/t/func_gconcat.test
index 826e00bf74f..1026ca67a43 100644
--- a/mysql-test/t/func_gconcat.test
+++ b/mysql-test/t/func_gconcat.test
@@ -640,4 +640,21 @@ SELECT GROUP_CONCAT(DISTINCT b, a ORDER BY b) FROM t1;
 
 DROP TABLE t1, t2, t3;
 
+#
+# Bug #34747: crash in debug assertion check after derived table
+#
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (),();
+SELECT s1.d1 FROM
+(
+ SELECT
+  t1.a as d1,
+  GROUP_CONCAT(DISTINCT t1.a) AS d2
+ FROM
+  t1 AS t1,
+  t1 AS t2
+ GROUP BY 1
+) AS s1;
+DROP TABLE t1;
+
 --echo End of 5.0 tests
diff --git a/mysql-test/t/subselect.test b/mysql-test/t/subselect.test
index c86b0fefbdc..fb3e59cc9d6 100644
--- a/mysql-test/t/subselect.test
+++ b/mysql-test/t/subselect.test
@@ -3015,6 +3015,52 @@ INSERT INTO t2 VALUES (103, 203);
 SELECT ((a1,a2) IN (SELECT * FROM t2 WHERE b2 > 0)) IS NULL FROM t1;
 DROP TABLE t1, t2;
 
+#
+# Bug31048: Many nested subqueries may cause server crash.
+#
+create table t1(a int,b int,key(a),key(b));
+insert into t1(a,b) values (1,2),(2,1),(2,3),(3,4),(5,4),(5,5),
+  (6,7),(7,4),(5,3);
+
+let $nesting= 26;
+let $should_work_nesting= 5;
+let $start= select sum(a),a from t1 where a> ( select sum(a) from t1 ;
+let $end= )group by a ;
+let $start_app= where a> ( select sum(a) from t1 ;
+let $end_pre= )group by b limit 1 ;
+
+--disable_result_log
+--disable_query_log
+# At least 4 level nesting should work without errors
+while ($should_work_nesting)
+{
+--echo $should_work_nesting
+  eval $start $end;
+  eval explain $start $end;
+  let $start= $start
+  $start_app;
+  let $end= $end_pre
+  $end;
+  dec $should_work_nesting;
+}
+# Other may fail with the 'stack overrun error'
+while ($nesting)
+{
+--echo $nesting
+--error 0,1436
+  eval $start $end;
+--error 0,1436
+  eval explain $start $end;
+  let $start= $start
+  $start_app;
+  let $end= $end_pre
+  $end;
+  dec $nesting;
+}
+--enable_result_log
+--enable_query_log
+drop table t1;
+
 #
 # Bug #28076: inconsistent binary/varbinary comparison
 #
diff --git a/sql/item_sum.cc b/sql/item_sum.cc
index d7b945cbd50..96effc36485 100644
--- a/sql/item_sum.cc
+++ b/sql/item_sum.cc
@@ -3494,6 +3494,6 @@ void Item_func_group_concat::print(String *str)
 
 Item_func_group_concat::~Item_func_group_concat()
 {
-  if (unique_filter) 
+  if (!original && unique_filter)
     delete unique_filter;    
 }