diff --git a/scripts/bootstrap-to-docker.sh b/scripts/bootstrap-to-docker.sh
index 11ce0aa..75ee8c5 100755
--- a/scripts/bootstrap-to-docker.sh
+++ b/scripts/bootstrap-to-docker.sh
@@ -143,13 +143,13 @@ for ((i=0; i<${#distros[@]}; ++i)); do
             fi
             echo " ----    mount filesystems in ${tmpdir}/${distro}-${arch}" 1>&2
             for x in proc sys dev; do
-                if mount | grep -q "${tmpdir}/${distro}-${arch}"/$x/; then
-                    umount -flr "${tmpdir}/${distro}-${arch}"/$x/
+                if mount | grep -q "${tmpdir}/${distro}-${arch}"/$x; then
+                    sudo umount -flr "${tmpdir}/${distro}-${arch}"/$x
                 fi
             done
-            sudo mount -t proc proc "${tmpdir}/${distro}-${arch}"/proc/
-            sudo mount -t sysfs sys "${tmpdir}/${distro}-${arch}"/sys/
-            sudo mount -o bind /dev "${tmpdir}/${distro}-${arch}"/dev/
+            sudo mount -t proc proc "${tmpdir}/${distro}-${arch}"/proc
+            sudo mount -t sysfs sys "${tmpdir}/${distro}-${arch}"/sys
+            sudo mount -o bind /dev "${tmpdir}/${distro}-${arch}"/dev
             echo " ----    preconfigure debian packages in ${tmpdir}/${distro}-${arch}" 1>&2
             sudo chroot "${tmpdir}/${distro}-${arch}" debconf-set-selections <<EOF
 console-setup   console-setup/fontsize-fb47     select  8x16
@@ -196,8 +196,8 @@ EOF1
             sudo chroot "${tmpdir}/${distro}-${arch}" apt-get -o Acquire::ForceIPv4=true install -y ${instpkgs}
             echo " ----    unmount filesystems in ${tmpdir}/${distro}-${arch}" 1>&2
             for x in proc sys dev; do
-                if mount | grep -q "${tmpdir}/${distro}-${arch}"/$x/; then
-                    umount -flr "${tmpdir}/${distro}-${arch}"/$x/
+                if mount | grep -q "${tmpdir}/${distro}-${arch}"/$x; then
+                    sudo umount -flr "${tmpdir}/${distro}-${arch}"/$x
                 fi
             done
             echo " ----    import ${tmpdir}/${distro}-${arch} to ${docker_user}/${type}:${distro}-${arch}" 1>&2