diff --git a/mysql-test/suite/vcol/r/vcol_misc.result b/mysql-test/suite/vcol/r/vcol_misc.result
index 1a16fd1a3944e..b15a398d414d6 100644
--- a/mysql-test/suite/vcol/r/vcol_misc.result
+++ b/mysql-test/suite/vcol/r/vcol_misc.result
@@ -591,3 +591,9 @@ DROP TABLE t;
 #
 # End of 10.5 tests
 #
+SET tx_isolation='READ-UNCOMMITTED';
+CREATE TABLE t (a VARCHAR(10),b INT,c CHAR(10) GENERATED ALWAYS AS (a) VIRTUAL,KEY(b,c)) ENGINE=InnoDB;
+INSERT INTO t (a) VALUES ('A');
+SELECT * FROM t WHERE b IS NULL ORDER BY a;
+a	b	c
+A	NULL	A
diff --git a/mysql-test/suite/vcol/t/vcol_misc.test b/mysql-test/suite/vcol/t/vcol_misc.test
index 2709ff5b46535..d11fd642e9754 100644
--- a/mysql-test/suite/vcol/t/vcol_misc.test
+++ b/mysql-test/suite/vcol/t/vcol_misc.test
@@ -1,5 +1,6 @@
 --source include/have_ucs2.inc
 --source include/have_debug.inc
+--source include/have_innodb.inc
 
 let $MYSQLD_DATADIR= `select @@datadir`;
 
@@ -560,3 +561,12 @@ DROP TABLE t;
 --echo #
 --echo # End of 10.5 tests
 --echo #
+
+#
+# MDEV-36896 Assertion `marked_for_read()' failed in virtual String *Field_varstring::val_str(String *, String *)
+#
+
+SET tx_isolation='READ-UNCOMMITTED';
+CREATE TABLE t (a VARCHAR(10),b INT,c CHAR(10) GENERATED ALWAYS AS (a) VIRTUAL,KEY(b,c)) ENGINE=InnoDB;
+INSERT INTO t (a) VALUES ('A');
+SELECT * FROM t WHERE b IS NULL ORDER BY a;
diff --git a/sql/table.cc b/sql/table.cc
index 2b283fd93e1b8..89ecb49cc214c 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -9187,7 +9187,6 @@ int TABLE::update_virtual_field(Field *vf, bool ignore_warnings)
           TABLE::update_virtual_fields(handler *, enum_vcol_update_mode).
   */
   in_use->set_n_backup_active_arena(expr_arena, &backup_arena);
-  bitmap_clear_all(&tmp_set);
   vf->vcol_info->expr->walk(&Item::update_vcol_processor, 0, &tmp_set);
   DBUG_FIX_WRITE_SET(vf);
   vf->vcol_info->expr->save_in_field(vf, 0);