tpic: clean up better
diff --git a/src/cmd/tpic/mkfile b/src/cmd/tpic/mkfile
index 76bdcb3..319697e 100644
--- a/src/cmd/tpic/mkfile
+++ b/src/cmd/tpic/mkfile
@@ -37,3 +37,4 @@
 	rm lex.yy.c
 	mv lex.yy.$O picl.$O
 
+CLEANFILES=$CLEANFILES picy.c