diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index 9855251d404..f1aa2eb48ec 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -4165,6 +4165,7 @@ subselect_hash_sj_engine::make_unique_engine()
     DBUG_RETURN(NULL);
 
   tab->table= tmp_table;
+  tab->preread_init_done= FALSE;
   tab->ref.tmp_table_index_lookup_init(thd, tmp_key, it, FALSE);
 
   DBUG_RETURN(new subselect_uniquesubquery_engine(thd, tab, item,
diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index e66ffe3265e..745a805d992 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1672,6 +1672,7 @@ void st_select_lex::init_select()
   cond_value= having_value= Item::COND_UNDEF;
   inner_refs_list.empty();
   full_group_by_flag= 0;
+  insert_tables= 0;
   merged_into= 0;
 }
 
diff --git a/sql/table.cc b/sql/table.cc
index 898a42044d7..290a82eb56a 100644
--- a/sql/table.cc
+++ b/sql/table.cc
@@ -3797,7 +3797,6 @@ bool TABLE_LIST::prep_check_option(THD *thd, uint8 check_opt_type)
 
     if (where)
     {
-      DBUG_ASSERT(where->fixed);
       check_option= where->copy_andor_structure(thd);
     }
     if (is_cascaded)