diff --git a/mysql-test/main/enforce_storage_engine.result b/mysql-test/main/enforce_storage_engine.result
index c761277a5b0..cc91daa73b9 100644
--- a/mysql-test/main/enforce_storage_engine.result
+++ b/mysql-test/main/enforce_storage_engine.result
@@ -158,5 +158,12 @@ t3	CREATE TABLE `t3` (
   PRIMARY KEY (`c1`)
 ) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
 DROP TABLE t3;
+#
+# MDEV-21618 CREATE UNIQUE INDEX fails with "ERROR 1286 (42000): Unknown storage engine 'partition'"
+#
+SET SESSION enforce_storage_engine=MyISAM;
+CREATE TABLE t4 (a INT) ENGINE=MyISAM PARTITION BY HASH(a);
+CREATE INDEX x on t4 (a);
+DROP TABLE t4;
 SET SESSION enforce_storage_engine=NULL;
 SET GLOBAL enforce_storage_engine=NULL;
diff --git a/mysql-test/main/enforce_storage_engine.test b/mysql-test/main/enforce_storage_engine.test
index 6b422477fe6..7768ed1bf46 100644
--- a/mysql-test/main/enforce_storage_engine.test
+++ b/mysql-test/main/enforce_storage_engine.test
@@ -1,4 +1,5 @@
--- source include/not_embedded.inc
+--source include/not_embedded.inc
+--source include/have_partition.inc
 
 set local sql_mode="";
 set global sql_mode="";
@@ -107,5 +108,15 @@ ALTER TABLE t3 ADD COLUMN c3 INT;
 SHOW CREATE TABLE t3;
 DROP TABLE t3;
 
+--echo #
+--echo # MDEV-21618 CREATE UNIQUE INDEX fails with "ERROR 1286 (42000): Unknown storage engine 'partition'"
+--echo #
+SET SESSION enforce_storage_engine=MyISAM;
+
+CREATE TABLE t4 (a INT) ENGINE=MyISAM PARTITION BY HASH(a);
+CREATE INDEX x on t4 (a);
+
+DROP TABLE t4;
+
 SET SESSION enforce_storage_engine=NULL;
-SET GLOBAL enforce_storage_engine=NULL;
\ No newline at end of file
+SET GLOBAL enforce_storage_engine=NULL;
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 1a239b7d105..f0d6084bc7e 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -11528,13 +11528,18 @@ bool check_engine(THD *thd, const char *db_name,
   if (!*new_engine)
     DBUG_RETURN(true);
 
-  /* Enforced storage engine should not be used in
-  ALTER TABLE that does not use explicit ENGINE = x to
-  avoid unwanted unrelated changes.*/
-  if (!(thd->lex->sql_command == SQLCOM_ALTER_TABLE &&
-        !(create_info->used_fields & HA_CREATE_USED_ENGINE)))
-    enf_engine= thd->variables.enforced_table_plugin ?
-       plugin_hton(thd->variables.enforced_table_plugin) : NULL;
+  /*
+    Enforced storage engine should not be used in ALTER TABLE that does not
+    use explicit ENGINE = x to avoid unwanted unrelated changes. It should not
+    be used in CREATE INDEX too.
+  */
+  if (!((thd->lex->sql_command == SQLCOM_ALTER_TABLE &&
+             !(create_info->used_fields & HA_CREATE_USED_ENGINE)) ||
+         thd->lex->sql_command == SQLCOM_CREATE_INDEX))
+  {
+    plugin_ref enf_plugin= thd->variables.enforced_table_plugin;
+    enf_engine= enf_plugin ? plugin_hton(enf_plugin) : NULL;
+  }
 
   if (enf_engine && enf_engine != *new_engine)
   {