--- src/Mixfix/Makefile.in.orig	2011-04-27 22:08:31.000000000 -0700
+++ src/Mixfix/Makefile.in	2011-04-27 22:09:07.000000000 -0700
@@ -1166,7 +1166,7 @@
 
 surface.cc surface.h: surface.yy
 	$(BISON) -dv surface.yy -o surface.c
-	mv surface.c surface.cc
+	cp surface.c surface.cc
 
 #	According to the manual, automake is supposed to grok
 #	.ll files and do the right thing... but it doesn't
