diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index eef5671f9c3..d1c3bc25210 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -4191,11 +4191,6 @@ extern "C" unsigned long thd_get_thread_id(const MYSQL_THD thd)
   return((unsigned long)thd->thread_id);
 }
 
-extern "C" enum_tx_isolation thd_get_trx_isolation(const MYSQL_THD thd)
-{
-	return thd->tx_isolation;
-}
-
 /**
   Check if THD socket is still connected.
  */