diff --git a/share/mk/bsd.dtb.mk b/share/mk/bsd.dtb.mk
index 6a0e78a3c66d..718c41dab4fa 100644
--- a/share/mk/bsd.dtb.mk
+++ b/share/mk/bsd.dtb.mk
@@ -3,7 +3,8 @@
 # Search for kernel source tree in standard places.
 .if empty(KERNBUILDDIR)
 .if !defined(SYSDIR)
-.for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
+.for _dir in ${SRCTOP:D${SRCTOP}/sys} \
+    ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
     ${.CURDIR}/../../../../.. /sys /usr/src/sys
 .if !defined(SYSDIR) && exists(${_dir}/kern/) && exists(${_dir}/conf/kmod.mk)
 SYSDIR=	${_dir}
diff --git a/share/mk/bsd.kmod.mk b/share/mk/bsd.kmod.mk
index f754254b21bb..d790165623c3 100644
--- a/share/mk/bsd.kmod.mk
+++ b/share/mk/bsd.kmod.mk
@@ -3,7 +3,8 @@
 # Search for kernel source tree in standard places.
 .if empty(KERNBUILDDIR)
 .if !defined(SYSDIR)
-.for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
+.for _dir in ${SRCTOP:D${SRCTOP}/sys} \
+    ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
     ${.CURDIR}/../../../../.. /sys /usr/src/sys
 .if !defined(SYSDIR) && exists(${_dir}/kern/) && exists(${_dir}/conf/kmod.mk)
 SYSDIR=	${_dir:tA}
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 258686f18fd5..e1d6d69549a4 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -83,7 +83,8 @@ OBJCOPY?=	objcopy
 # Search for kernel source tree in standard places.
 .if empty(KERNBUILDDIR)
 .if !defined(SYSDIR)
-.for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. /sys /usr/src/sys
+.for _dir in ${SRCTOP:D${SRCTOP}/sys} \
+    ${.CURDIR}/../.. ${.CURDIR}/../../.. /sys /usr/src/sys
 .if !defined(SYSDIR) && exists(${_dir}/kern/)
 SYSDIR=	${_dir:tA}
 .endif