diff --git a/mysql-test/r/heap_btree.result b/mysql-test/r/heap_btree.result
index fd789a39d88..18d3dab1b06 100644
--- a/mysql-test/r/heap_btree.result
+++ b/mysql-test/r/heap_btree.result
@@ -280,6 +280,21 @@ a
 1
 1
 drop table t1;
+CREATE TABLE t1 (
+c1 CHAR(3),
+c2 INTEGER,
+KEY USING BTREE(c1),
+KEY USING BTREE(c2)
+) ENGINE= MEMORY;
+INSERT INTO t1 VALUES ('ABC',0), ('A',0), ('B',0), ('C',0);
+UPDATE t1 SET c2= c2 + 1 WHERE c1 = 'A';
+SELECT * FROM t1;
+c1	c2
+ABC	0
+A	1
+B	0
+C	0
+DROP TABLE t1;
 End of 4.1 tests
 CREATE TABLE t1(val INT, KEY USING BTREE(val)) ENGINE=memory;
 INSERT INTO t1 VALUES(0);
diff --git a/mysql-test/t/heap_btree.test b/mysql-test/t/heap_btree.test
index 68aa79834fc..8e745d7646d 100644
--- a/mysql-test/t/heap_btree.test
+++ b/mysql-test/t/heap_btree.test
@@ -182,6 +182,20 @@ delete from t1 where a >= 2;
 select a from t1 order by a;
 drop table t1;
 
+#
+# Bug#26996 - Update of a Field in a Memory Table ends with wrong result
+#
+CREATE TABLE t1 (
+  c1 CHAR(3),
+  c2 INTEGER,
+  KEY USING BTREE(c1),
+  KEY USING BTREE(c2)
+) ENGINE= MEMORY;
+INSERT INTO t1 VALUES ('ABC',0), ('A',0), ('B',0), ('C',0);
+UPDATE t1 SET c2= c2 + 1 WHERE c1 = 'A';
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo End of 4.1 tests
 
 #
diff --git a/storage/heap/hp_write.c b/storage/heap/hp_write.c
index 86e79c9d7ec..19215fcf017 100644
--- a/storage/heap/hp_write.c
+++ b/storage/heap/hp_write.c
@@ -105,7 +105,6 @@ int hp_rb_write_key(HP_INFO *info, HP_KEYDEF *keyinfo, const byte *record,
   heap_rb_param custom_arg;
   uint old_allocated;
 
-  info->last_pos= NULL; /* For heap_rnext/heap_rprev */
   custom_arg.keyseg= keyinfo->seg;
   custom_arg.key_length= hp_rb_make_key(keyinfo, info->recbuf, record, recpos);
   if (keyinfo->flag & HA_NOSAME)
diff --git a/storage/myisam/ha_myisam.cc b/storage/myisam/ha_myisam.cc
index 26a880bc704..505febf8828 100644
--- a/storage/myisam/ha_myisam.cc
+++ b/storage/myisam/ha_myisam.cc
@@ -632,6 +632,9 @@ bool ha_myisam::check_if_locking_is_allowed(uint sql_command,
 
 int ha_myisam::open(const char *name, int mode, uint test_if_locked)
 {
+  MI_KEYDEF *keyinfo;
+  MI_COLUMNDEF *recinfo= 0;
+  uint recs;
   uint i;
 
   /*
@@ -654,6 +657,26 @@ int ha_myisam::open(const char *name, int mode, uint test_if_locked)
 
   if (!(file=mi_open(name, mode, test_if_locked | HA_OPEN_FROM_SQL_LAYER)))
     return (my_errno ? my_errno : -1);
+  if (!table->s->tmp_table) /* No need to perform a check for tmp table */
+  {
+    if ((my_errno= table2myisam(table, &keyinfo, &recinfo, &recs)))
+    {
+      /* purecov: begin inspected */
+      DBUG_PRINT("error", ("Failed to convert TABLE object to MyISAM "
+                           "key and column definition"));
+      goto err;
+      /* purecov: end */
+    }
+    if (check_definition(keyinfo, recinfo, table->s->keys, recs,
+                         file->s->keyinfo, file->s->rec,
+                         file->s->base.keys, file->s->base.fields, true))
+    {
+      /* purecov: begin inspected */
+      my_errno= HA_ERR_CRASHED;
+      goto err;
+      /* purecov: end */
+    }
+  }
   
   if (test_if_locked & (HA_OPEN_IGNORE_IF_LOCKED | HA_OPEN_TMP_TABLE))
     VOID(mi_extra(file, HA_EXTRA_NO_WAIT_LOCK, 0));
@@ -674,7 +697,18 @@ int ha_myisam::open(const char *name, int mode, uint test_if_locked)
         (struct st_mysql_ftparser *)parser->plugin->info;
     table->key_info[i].block_size= file->s->keyinfo[i].block_length;
   }
-  return (0);
+  my_errno= 0;
+  goto end;
+ err:
+  this->close();
+ end:
+  /*
+    Both recinfo and keydef are allocated by my_multi_malloc(), thus only
+    recinfo must be freed.
+  */
+  if (recinfo)
+    my_free((gptr) recinfo, MYF(0));
+  return my_errno;
 }
 
 int ha_myisam::close(void)