diff --git a/share/mk/bsd.kmod.mk b/share/mk/bsd.kmod.mk
index 09ac8e3de34..d0ac48b6330 100644
--- a/share/mk/bsd.kmod.mk
+++ b/share/mk/bsd.kmod.mk
@@ -4,7 +4,7 @@
 .for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. ${.CURDIR}/../../../.. \
     ${.CURDIR}/../../../../.. /sys /usr/src/sys
 .if !defined(SYSDIR) && exists(${_dir}/kern/) && exists(${_dir}/conf/kmod.mk)
-SYSDIR=	${_dir}
+SYSDIR=	${_dir:tA}
 .endif
 .endfor
 .if !defined(SYSDIR) || !exists(${SYSDIR}/kern/) || \
diff --git a/sys/conf/kern.post.mk b/sys/conf/kern.post.mk
index 19e8e2e2790..b81b9d95785 100644
--- a/sys/conf/kern.post.mk
+++ b/sys/conf/kern.post.mk
@@ -12,7 +12,7 @@
 .if defined(DESTDIR)
 MKMODULESENV+=	DESTDIR="${DESTDIR}"
 .endif
-SYSDIR?= ${S:C;^[^/];${.CURDIR}/&;}
+SYSDIR?= ${S:C;^[^/];${.CURDIR}/&;:tA}
 MKMODULESENV+=	KERNBUILDDIR="${.CURDIR}" SYSDIR="${SYSDIR}"
 
 .if defined(CONF_CFLAGS)
diff --git a/sys/conf/kmod.mk b/sys/conf/kmod.mk
index 570a34f4d1d..8bf017e68e9 100644
--- a/sys/conf/kmod.mk
+++ b/sys/conf/kmod.mk
@@ -269,7 +269,7 @@ ${OBJS}: ${_link}
 # Search for kernel source tree in standard places.
 .for _dir in ${.CURDIR}/../.. ${.CURDIR}/../../.. /sys /usr/src/sys
 .if !defined(SYSDIR) && exists(${_dir}/kern/)
-SYSDIR=	${_dir}
+SYSDIR=	${_dir:tA}
 .endif
 .endfor
 .if !defined(SYSDIR) || !exists(${SYSDIR}/kern/)