diff --git a/mysql-test/r/win.result b/mysql-test/r/win.result
index e3cb40e8343..b519b2bb223 100644
--- a/mysql-test/r/win.result
+++ b/mysql-test/r/win.result
@@ -3299,3 +3299,18 @@ ROW_NUMBER() OVER()	i
 SELECT ROW_NUMBER() OVER(), i FROM t1 WHERE 0;
 ROW_NUMBER() OVER()	i
 DROP TABLE t1;
+#
+# MDEV-15853: Assertion `tab->filesort_result == 0' failed
+#
+CREATE TABLE t1 ( a1 int);
+insert into t1 values (1),(2),(3);
+CREATE TABLE t2 (b1 int, a1 int, a2 int);
+insert into t2 values (1,2,3),(2,3,4),(3,4,5);
+SELECT COUNT(DISTINCT t2.a2),
+rank() OVER (ORDER BY t2.b1)
+FROM t2 ,t1 GROUP BY t2.b1 ORDER BY t1.a1;
+COUNT(DISTINCT t2.a2)	rank() OVER (ORDER BY t2.b1)
+1	1
+1	2
+1	3
+DROP TABLE t1,t2;
diff --git a/mysql-test/t/win.test b/mysql-test/t/win.test
index 95ffb6d9909..b354a55d0d6 100644
--- a/mysql-test/t/win.test
+++ b/mysql-test/t/win.test
@@ -2067,3 +2067,18 @@ SELECT DISTINCT ROW_NUMBER() OVER(), i FROM t1 WHERE 0;
 SELECT ROW_NUMBER() OVER(), i FROM t1 WHERE 0;
 DROP TABLE t1;
 
+--echo #
+--echo # MDEV-15853: Assertion `tab->filesort_result == 0' failed
+--echo #
+
+CREATE TABLE t1 ( a1 int);
+insert into t1 values (1),(2),(3);
+
+CREATE TABLE t2 (b1 int, a1 int, a2 int);
+insert into t2 values (1,2,3),(2,3,4),(3,4,5);
+
+--sorted_result
+SELECT COUNT(DISTINCT t2.a2),
+      rank() OVER (ORDER BY t2.b1)
+FROM t2 ,t1 GROUP BY t2.b1 ORDER BY t1.a1;
+DROP TABLE t1,t2;
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 4df4c0c87e1..4cd4754596b 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -2851,7 +2851,7 @@ bool JOIN::make_aggr_tables_info()
     - duplicate value removal
     Both of these operations are done after window function computation step.
   */
-  curr_tab= join_tab + exec_join_tab_cnt() + aggr_tables - 1;
+  curr_tab= join_tab + total_join_tab_cnt();
   if (select_lex->window_funcs.elements)
   {
     curr_tab->window_funcs_step= new Window_funcs_computation;
diff --git a/sql/sql_select.h b/sql/sql_select.h
index 2003cc1211b..a134d601c76 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -1503,6 +1503,15 @@ public:
   /* Number of tables actually joined at the top level */
   uint exec_join_tab_cnt() { return tables_list ? top_join_tab_count : 0; }
 
+  /*
+    Number of tables in the join which also includes the temporary tables
+    created for GROUP BY, DISTINCT , WINDOW FUNCTION etc.
+  */
+  uint total_join_tab_cnt()
+  {
+    return exec_join_tab_cnt() + aggr_tables - 1;
+  }
+
   int prepare(TABLE_LIST *tables, uint wind_num,
 	      COND *conds, uint og_num, ORDER *order, bool skip_order_by,
               ORDER *group, Item *having, ORDER *proc_param, SELECT_LEX *select,
diff --git a/sql/sql_window.cc b/sql/sql_window.cc
index 4e1e64365ae..cd09e174808 100644
--- a/sql/sql_window.cc
+++ b/sql/sql_window.cc
@@ -2754,7 +2754,7 @@ bool Window_func_runner::exec(THD *thd, TABLE *tbl, SORT_INFO *filesort_result)
 bool Window_funcs_sort::exec(JOIN *join)
 {
   THD *thd= join->thd;
-  JOIN_TAB *join_tab= join->join_tab + join->exec_join_tab_cnt();
+  JOIN_TAB *join_tab= join->join_tab + join->total_join_tab_cnt();
 
   /* Sort the table based on the most specific sorting criteria of
      the window functions. */