diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index 05706fa85be..6db81ebfc51 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -7,9 +7,6 @@
 .include <bsd.compiler.mk>
 .include "kern.opts.mk"
 
-# backwards compat option for older systems.
-MACHINE_CPUARCH?=${MACHINE_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb)?/arm/:C/powerpc64/powerpc/}
-
 # Can be overridden by makeoptions or /etc/make.conf
 KERNEL_KO?=	kernel
 KERNEL?=	kernel
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 4f85ab4185a..242c3c68096 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -60,9 +60,6 @@
 #		Unload a module.
 #
 
-# backwards compat option for older systems.
-MACHINE_CPUARCH?=${MACHINE_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb)?/arm/:C/powerpc64/powerpc/}
-
 AWK?=		awk
 KMODLOAD?=	/sbin/kldload
 KMODUNLOAD?=	/sbin/kldunload