make mac work
diff --git a/include/mach.h b/include/mach.h
index 2a1b168..89c3f85 100644
--- a/include/mach.h
+++ b/include/mach.h
@@ -476,7 +476,7 @@
 
 void		_addhdr(Fhdr*);
 void		_delhdr(Fhdr*);
-Fhdr*	fhdrlist;
+extern Fhdr*	fhdrlist;
 
 Symbol*	flookupsym(Fhdr*, char*);
 Symbol*	ffindsym(Fhdr*, Loc, uint);