diff --git a/mysql-test/r/selectivity.result b/mysql-test/r/selectivity.result
index 2ab143d6b14..fb2329abd33 100644
--- a/mysql-test/r/selectivity.result
+++ b/mysql-test/r/selectivity.result
@@ -935,4 +935,33 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (isnull(`test`.`t
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
 DROP TABLE t1;
 set use_stat_tables=@save_use_stat_tables;
+#
+# Bug mdev-4378: 2-way join with a materialized IN subquery in WHERE   
+#                when optimizer_use_condition_selectivity=4
+#
+set use_stat_tables=PREFERABLY;
+set histogram_size=50;
+set histogram_type=SINGLE_PREC_HB;
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (8),(9),(6);
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (8),(1),(8),(9),(24),(6),(1),(6),(2),(4);
+CREATE TABLE t3 (ln VARCHAR(16)) ENGINE=MyISAM;
+INSERT INTO t3 VALUES 
+('smith'),('black'),('white'),('jones'),
+('brown'),('taylor'),('anderson'),('taylor');
+ANALYZE TABLE t1, t2, t3;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+test.t2	analyze	status	OK
+test.t3	analyze	status	OK
+FLUSH TABLES;
+set  optimizer_use_condition_selectivity=4;
+SELECT * FROM t1, t2 WHERE 'garcia' IN ( SELECT MIN( ln ) FROM t3 WHERE ln = 'sun' );
+a	b
+set histogram_size=@save_histogram_size;
+set histogram_type=@save_histogram_type;
+set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+DROP TABLE t1,t2,t3;
+set use_stat_tables=@save_use_stat_tables;
 set use_stat_tables=@save_use_stat_tables;
diff --git a/mysql-test/r/selectivity_innodb.result b/mysql-test/r/selectivity_innodb.result
index 2a639e922af..8123641ddea 100644
--- a/mysql-test/r/selectivity_innodb.result
+++ b/mysql-test/r/selectivity_innodb.result
@@ -943,6 +943,35 @@ Note	1003	select `test`.`t1`.`a` AS `a` from `test`.`t1` where (isnull(`test`.`t
 set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
 DROP TABLE t1;
 set use_stat_tables=@save_use_stat_tables;
+#
+# Bug mdev-4378: 2-way join with a materialized IN subquery in WHERE   
+#                when optimizer_use_condition_selectivity=4
+#
+set use_stat_tables=PREFERABLY;
+set histogram_size=50;
+set histogram_type=SINGLE_PREC_HB;
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (8),(9),(6);
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (8),(1),(8),(9),(24),(6),(1),(6),(2),(4);
+CREATE TABLE t3 (ln VARCHAR(16)) ENGINE=MyISAM;
+INSERT INTO t3 VALUES 
+('smith'),('black'),('white'),('jones'),
+('brown'),('taylor'),('anderson'),('taylor');
+ANALYZE TABLE t1, t2, t3;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+test.t2	analyze	status	OK
+test.t3	analyze	status	OK
+FLUSH TABLES;
+set  optimizer_use_condition_selectivity=4;
+SELECT * FROM t1, t2 WHERE 'garcia' IN ( SELECT MIN( ln ) FROM t3 WHERE ln = 'sun' );
+a	b
+set histogram_size=@save_histogram_size;
+set histogram_type=@save_histogram_type;
+set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+DROP TABLE t1,t2,t3;
+set use_stat_tables=@save_use_stat_tables;
 set use_stat_tables=@save_use_stat_tables;
 set optimizer_switch=@save_optimizer_switch_for_selectivity_test;
 SET SESSION STORAGE_ENGINE=DEFAULT;
diff --git a/mysql-test/t/selectivity.test b/mysql-test/t/selectivity.test
index d8ab19ac28a..ddc74a5b34f 100644
--- a/mysql-test/t/selectivity.test
+++ b/mysql-test/t/selectivity.test
@@ -526,5 +526,40 @@ DROP TABLE t1;
 
 set use_stat_tables=@save_use_stat_tables;
 
+--echo #
+--echo # Bug mdev-4378: 2-way join with a materialized IN subquery in WHERE   
+--echo #                when optimizer_use_condition_selectivity=4
+--echo #
+
+set use_stat_tables=PREFERABLY;
+set histogram_size=50;
+set histogram_type=SINGLE_PREC_HB;
+
+CREATE TABLE t1 (a INT) ENGINE=MyISAM;
+INSERT INTO t1 VALUES (8),(9),(6);
+
+CREATE TABLE t2 (b INT) ENGINE=MyISAM;
+INSERT INTO t2 VALUES (8),(1),(8),(9),(24),(6),(1),(6),(2),(4);
+
+CREATE TABLE t3 (ln VARCHAR(16)) ENGINE=MyISAM;
+INSERT INTO t3 VALUES 
+('smith'),('black'),('white'),('jones'),
+('brown'),('taylor'),('anderson'),('taylor');
+
+ANALYZE TABLE t1, t2, t3;
+FLUSH TABLES;
+
+set  optimizer_use_condition_selectivity=4;
+
+SELECT * FROM t1, t2 WHERE 'garcia' IN ( SELECT MIN( ln ) FROM t3 WHERE ln = 'sun' );
+
+set histogram_size=@save_histogram_size;
+set histogram_type=@save_histogram_type;
+set optimizer_use_condition_selectivity=@save_optimizer_use_condition_selectivity;
+
+DROP TABLE t1,t2,t3;
+
+set use_stat_tables=@save_use_stat_tables;
+
 
 set use_stat_tables=@save_use_stat_tables;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 368844c2379..6ee88a72795 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -14335,6 +14335,7 @@ Field *create_tmp_field_from_field(THD *thd, Field *org_field,
       ((Field_double *) new_field)->not_fixed= TRUE;
     new_field->vcol_info= 0;
     new_field->stored_in_db= TRUE;
+    new_field->cond_selectivity= 1.0;
   }
   return new_field;
 }