diff --git a/lisp/Config.pmax_mach b/lisp/Config.pmax_mach
index 709a20fffdee58321c12bc49163f6d932767ab25..4bf907f48a4cfc08a64dbaaa937b471f0e738405 100644
--- a/lisp/Config.pmax_mach
+++ b/lisp/Config.pmax_mach
@@ -4,7 +4,7 @@ CPP = /usr/cs/lib/cpp
 CFLAGS = -g
 ASFLAGS = -g
 NM = nm -gp
-UNDEFSYMPATTERN = &
+UNDEFSYMPATTERN=-Xlinker -u -Xlinker &
 ASSEM_SRC = mips-assem.S
 ARCH_SRC = mips-arch.c
 OS_SRC = mach-os.c