--- cmd4.c.org
+++ cmd4.c
@@ -1407,6 +1407,13 @@
 				break;
 			}
 
+			case 't':
+			case 'T':
+			{
+				(*option_info[opt[k]].o_var) = !(*option_info[opt[k]].o_var);
+				break;
+			}
+
 			default:
 			{
 				bell();