diff --git a/pkgs/build-support/vm/default.nix b/pkgs/build-support/vm/default.nix
index 5e0d77129c5..4e63d8082c3 100644
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -216,7 +216,7 @@ rec {
       -nographic -no-reboot \
       -net nic,model=virtio \
       -chardev socket,id=samba,path=./samba \
-      -net user,guestfwd=tcp:10.0.2.4:139-chardev:samba \
+      -net user,guestfwd=tcp:10.0.2.4:445-chardev:samba \
       -drive file=$diskImage,if=virtio,boot=on,cache=writeback,werror=report \
       -kernel ${kernel}/bzImage \
       -initrd ${initrd}/initrd \
@@ -247,7 +247,7 @@ rec {
       SMB
 
       rm -f ./samba
-      ${socat}/bin/socat unix-listen:./samba exec:"${samba}/sbin/smbd -s $TMPDIR/smb.conf",nofork > /dev/null 2>&1 &
+      ${socat}/bin/socat unix-listen:./samba exec:"${utillinux}/bin/setsid ${samba}/sbin/smbd -s $TMPDIR/smb.conf",nofork > /dev/null 2>&1 &
       while [ ! -e ./samba ]; do sleep 0.1; done # ugly
     '';