diff --git a/mysql-test/main/explain_non_select.result b/mysql-test/main/explain_non_select.result
index d60f10f85c8..1200a3f9400 100644
--- a/mysql-test/main/explain_non_select.result
+++ b/mysql-test/main/explain_non_select.result
@@ -277,3 +277,22 @@ EXECUTE stmt;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	
 drop table t1,t2;
+#
+# MDEV-31224: EXPLAIN EXTENDED for multi-table update of system table
+#
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (1),(2);
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3);
+EXPLAIN EXTENDED UPDATE t1, t2 SET b = 4 WHERE a IN (6,2);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t2	system	NULL	NULL	NULL	NULL	1	100.00	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	update `test`.`t1` set `test`.`t2`.`b` = 4 where `test`.`t1`.`a` in (6,2)
+UPDATE t1, t2 SET b = 4 WHERE a IN (6,2);
+SELECT * from t2;
+b
+4
+DROP TABLE t1, t2;
+# End of 10.4 tests
diff --git a/mysql-test/main/explain_non_select.test b/mysql-test/main/explain_non_select.test
index d9ff0fb7245..f87a5d9ec8d 100644
--- a/mysql-test/main/explain_non_select.test
+++ b/mysql-test/main/explain_non_select.test
@@ -250,3 +250,23 @@ PREPARE stmt FROM 'EXPLAIN INSERT INTO t1 SELECT * FROM t2';
 EXECUTE stmt;
 drop table t1,t2;
 
+--echo #
+--echo # MDEV-31224: EXPLAIN EXTENDED for multi-table update of system table
+--echo #
+
+CREATE TABLE t1 (a INT);
+INSERT INTO t1 VALUES (1),(2);
+
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (3);
+
+let $q=
+UPDATE t1, t2 SET b = 4 WHERE a IN (6,2);
+
+eval EXPLAIN EXTENDED $q;
+eval $q;
+SELECT * from t2;
+
+DROP TABLE t1, t2;
+
+--echo # End of 10.4 tests
diff --git a/mysql-test/main/myisam_explain_non_select_all.result b/mysql-test/main/myisam_explain_non_select_all.result
index 3ca9629d027..b515cb4fd83 100644
--- a/mysql-test/main/myisam_explain_non_select_all.result
+++ b/mysql-test/main/myisam_explain_non_select_all.result
@@ -2689,7 +2689,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t2	system	NULL	NULL	NULL	NULL	0	0.00	Const row not found
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	
 Warnings:
-Note	1003	update `test`.`t1` set NULL = 10
+Note	1003	update `test`.`t1` set `test`.`t2`.`c2` = 10
 # Status of EXPLAIN EXTENDED query
 Variable_name	Value
 Handler_read_key	7
@@ -2734,7 +2734,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t2	system	NULL	NULL	NULL	NULL	0	0.00	Const row not found
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 Warnings:
-Note	1003	update `test`.`t1` set NULL = 10 where `test`.`t1`.`c3` = 10
+Note	1003	update `test`.`t1` set `test`.`t2`.`c2` = 10 where `test`.`t1`.`c3` = 10
 # Status of EXPLAIN EXTENDED query
 Variable_name	Value
 Handler_read_key	7
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index bfe17bb43e1..cb60b3442d8 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -28138,7 +28138,7 @@ void st_select_lex::print_set_clause(THD *thd, String *str,
     else
       str->append(',');
 
-    item->print(str, query_type);
+    item->print(str, (enum_query_type) (query_type | QT_NO_DATA_EXPANSION));
     str->append(STRING_WITH_LEN(" = "));
     val->print(str, query_type);
   }