diff --git a/mysql-test/r/subselect_mat_cost_bugs.result b/mysql-test/r/subselect_mat_cost_bugs.result
index 919a6c6d38d..1e69578dffd 100644
--- a/mysql-test/r/subselect_mat_cost_bugs.result
+++ b/mysql-test/r/subselect_mat_cost_bugs.result
@@ -295,3 +295,24 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 select c1 from t1 where c1 in (select kp1 from t2 where kp2 = 10 and c2 = 4) or c1 > 7;
 c1
 drop table t1, t2;
+#
+# LP BUG#800679: Assertion `outer_join->table_count > 0' failed in
+# JOIN::choose_subquery_plan() with materialization=on,semijoin=off
+#
+CREATE TABLE t1 ( f1 int);
+insert into t1 values (1),(2);
+CREATE TABLE t2 ( f1 int);
+insert into t2 values (1),(2);
+SET @@optimizer_switch='materialization=on,semijoin=off';
+EXPLAIN
+SELECT * FROM t1
+WHERE (f1) IN (SELECT f1 FROM t2)
+LIMIT 0;
+id      select_type     table   type    possible_keys   key     key_len ref     rows    Extra
+1       PRIMARY NULL    NULL    NULL    NULL    NULL    NULL    NULL    Impossible WHERE
+2       DEPENDENT SUBQUERY      t2      ALL     NULL    NULL    NULL    NULL    2       Using where
+SELECT * FROM t1
+WHERE (f1) IN (SELECT f1 FROM t2)
+LIMIT 0;
+f1
+drop table t1, t2;
diff --git a/mysql-test/t/subselect_mat_cost_bugs.test b/mysql-test/t/subselect_mat_cost_bugs.test
index 0240c9203b3..37c7b617760 100644
--- a/mysql-test/t/subselect_mat_cost_bugs.test
+++ b/mysql-test/t/subselect_mat_cost_bugs.test
@@ -326,3 +326,26 @@ select c1 from t1 where c1 in (select kp1 from t2 where kp2 = 10 and c2 = 4) or
 select c1 from t1 where c1 in (select kp1 from t2 where kp2 = 10 and c2 = 4) or c1 > 7;
 
 drop table t1, t2;
+
+--echo #
+--echo # LP BUG#800679: Assertion `outer_join->table_count > 0' failed in
+--echo # JOIN::choose_subquery_plan() with materialization=on,semijoin=off
+--echo #
+
+CREATE TABLE t1 ( f1 int);
+insert into t1 values (1),(2);
+CREATE TABLE t2 ( f1 int);
+insert into t2 values (1),(2);
+
+SET @@optimizer_switch='materialization=on,semijoin=off';
+
+EXPLAIN
+SELECT * FROM t1
+WHERE (f1) IN (SELECT f1 FROM t2)
+LIMIT 0;
+
+SELECT * FROM t1
+WHERE (f1) IN (SELECT f1 FROM t2)
+LIMIT 0;
+
+drop table t1, t2;
diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc
index db7290af662..51a18956c5d 100644
--- a/sql/opt_subselect.cc
+++ b/sql/opt_subselect.cc
@@ -4360,7 +4360,7 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
       by the IN predicate.
     */
     outer_join= unit->outer_select() ? unit->outer_select()->join : NULL;
-    if (outer_join)
+    if (outer_join && outer_join->table_count > 0)
     {
       /*
         The index of the last JOIN_TAB in the outer JOIN where in_subs is
@@ -4373,7 +4373,6 @@ bool JOIN::choose_subquery_plan(table_map join_tables)
         JOIN_TAB, and their join_tab_idx remains MAX_TABLES. Such predicates
         are evaluated for each complete row of the outer join.
       */
-      DBUG_ASSERT(outer_join->table_count > 0);
       max_outer_join_tab_idx= (in_subs->get_join_tab_idx() == MAX_TABLES) ?
                                outer_join->table_count - 1:
                                in_subs->get_join_tab_idx();