diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index a5f6cfeb4fb..9b6ff826dec 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -2028,9 +2028,7 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
     break;
   case Item_func::OPTIMIZE_KEY:
     if (cond_func->key_item()->real_item()->type() == Item::FIELD_ITEM &&
-	// field from outer query can't be used as key
-	!((Item_field*) (cond_func->key_item()->real_item()))
-	->depended_from)
+	!(cond_func->used_tables() & OUTER_REF_TABLE_BIT))
       add_key_field(key_fields,*and_level,
 		    ((Item_field*) (cond_func->key_item()->real_item()))
 		    ->field,
@@ -2042,9 +2040,7 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
 		     cond_func->functype() == Item_func::EQUAL_FUNC);
 
     if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM &&
-	// field from outer query can't be used as key
-	!((Item_field*) (cond_func->arguments()[0]->real_item()))
-	->depended_from)
+	!(cond_func->arguments()[0]->used_tables() & OUTER_REF_TABLE_BIT))
     {
       add_key_field(key_fields,*and_level,
 		    ((Item_field*) (cond_func->arguments()[0])->real_item())
@@ -2054,9 +2050,7 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
     }
     if (cond_func->arguments()[1]->real_item()->type() == Item::FIELD_ITEM &&
 	cond_func->functype() != Item_func::LIKE_FUNC &&
-	// field from outer query can't be used as key
-	!((Item_field*) (cond_func->arguments()[1]->real_item()))
-	->depended_from)
+	!(cond_func->arguments()[0]->used_tables() & OUTER_REF_TABLE_BIT))
     {
       add_key_field(key_fields,*and_level,
 		    ((Item_field*) (cond_func->arguments()[1])->real_item())
@@ -2069,9 +2063,7 @@ add_key_fields(JOIN_TAB *stat,KEY_FIELD **key_fields,uint *and_level,
   case Item_func::OPTIMIZE_NULL:
     /* column_name IS [NOT] NULL */
     if (cond_func->arguments()[0]->real_item()->type() == Item::FIELD_ITEM &&
-	// field from outer query can't be used as key
-	!((Item_field*) (cond_func->arguments()[0]->real_item()))
-	->depended_from)
+	!(cond_func->used_tables() & OUTER_REF_TABLE_BIT))
     {
       add_key_field(key_fields,*and_level,
 		    ((Item_field*) (cond_func->arguments()[0])->real_item())