diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -50,6 +50,10 @@
 MKMODULESENV+=	GCOV_CFLAGS="${GCOV_CFLAGS}"
 .endif
 
+.if !empty(COMPAT_FREEBSD32_ENABLED)
+MKMODULESENV+=	COMPAT_FREEBSD32_ENABLED="yes"
+.endif
+
 # Allow overriding the kernel debug directory, so kernel and user debug may be
 # installed in different directories. Setting it to "" restores the historical
 # behavior of installing debug files in the kernel directory.
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -91,7 +91,9 @@
 CFLAGS+=	-fno-common
 
 # XXX LOCORE means "don't declare C stuff" not "for locore.s".
-ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS} ${ASM_CFLAGS.${.IMPSRC:T}} 
+ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS} ${ASM_CFLAGS.${.IMPSRC:T}}
+
+COMPAT_FREEBSD32_ENABLED!= grep COMPAT_FREEBSD32 opt_global.h || true ; echo
 
 KASAN_ENABLED!=	grep KASAN opt_global.h || true ; echo
 .if !empty(KASAN_ENABLED)
diff --git a/sys/modules/Makefile b/sys/modules/Makefile
--- a/sys/modules/Makefile
+++ b/sys/modules/Makefile
@@ -623,7 +623,9 @@
 
 .if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
 _agp=		agp
+.if ${MACHINE_CPUARCH} == "i386" || !empty(COMPAT_FREEBSD32_ENABLED)
 _aout=		aout
+.endif
 _bios=		bios
 .if ${MK_SOURCELESS_UCODE} != "no"
 _bxe=		bxe