diff --git a/mk/os-BSD.mk b/mk/os-BSD.mk
index 3032a076..d91ccef9 100644
--- a/mk/os-BSD.mk
+++ b/mk/os-BSD.mk
@@ -2,5 +2,4 @@
 
 # Generic definitions
 
-SUBOS=		BSD
 LIBKVM?=	-lkvm
diff --git a/mk/os-Linux.mk b/mk/os-Linux.mk
index 8aa32b36..c79bb576 100644
--- a/mk/os-Linux.mk
+++ b/mk/os-Linux.mk
@@ -1,5 +1,4 @@
 # Copyright 2008 Roy Marples
 
-SUBOS=		Linux
 CFLAGS+=	-D_BSD_SOURCE -D_XOPEN_SOURCE=600
 LIBDL=		-Wl,-Bdynamic -ldl