diff --git a/mysql-test/lib/v1/mysql-test-run.pl b/mysql-test/lib/v1/mysql-test-run.pl
index 12792b297ac..857a28d648f 100755
--- a/mysql-test/lib/v1/mysql-test-run.pl
+++ b/mysql-test/lib/v1/mysql-test-run.pl
@@ -4088,7 +4088,7 @@ sub mysqld_arguments ($$$$) {
   }
 
   mtr_add_arg($args, "%s--key_buffer_size=1M", $prefix);
-  mtr_add_arg($args, "%s--sort_buffer=256K", $prefix);
+  mtr_add_arg($args, "%s--sort_buffer_size=256K", $prefix);
   mtr_add_arg($args, "%s--max_heap_table_size=1M", $prefix);
 
   if ( $opt_ssl_supported )