diff --git a/userlib/Makefile b/userlib/Makefile
index 79d7bd9..73d3ed9 100644
--- a/userlib/Makefile
+++ b/userlib/Makefile
@@ -1,7 +1,7 @@
 TOPDIR = ../
 include $(TOPDIR)/Makefile.rules
 
-default: sys.a libnachos.a
+default: sys.o libnachos.o
 
 clean:
-	$(RM) libnachos.a sys.a libnachos.o sys.o
\ No newline at end of file
+	$(RM) libnachos.o sys.o
\ No newline at end of file