diff --git a/des/sim/vhdl/makefile b/des/sim/vhdl/makefile
index b2db549..c70c4c8 100644
--- a/des/sim/vhdl/makefile
+++ b/des/sim/vhdl/makefile
@@ -34,6 +34,7 @@ wave : tb_des.ghw
 
 clean :
 	echo "# cleaning simulation files"
+	rm -f tb_des
 	rm -f *.o
 	rm -f tb_des.ghw
 	rm -f work*.cf