diff --git a/pkgs/build-support/vm/default.nix b/pkgs/build-support/vm/default.nix
index 52b50adbfecf..b1eb82ed8303 100644
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -123,14 +123,14 @@ rec {
 
     echo "mounting Nix store..."
     mkdir -p /fs/nix/store
-    mount -t cifs //10.0.2.4/store /fs/nix/store -o guest,sec=ntlm
+    mount -t cifs //10.0.2.4/store /fs/nix/store -o guest,sec=none,sec=ntlm
 
     mkdir -p /fs/tmp
     mount -t tmpfs -o "mode=755" none /fs/tmp
 
     echo "mounting host's temporary directory..."
     mkdir -p /fs/tmp/xchg
-    mount -t cifs //10.0.2.4/xchg /fs/tmp/xchg -o guest,sec=ntlm
+    mount -t cifs //10.0.2.4/xchg /fs/tmp/xchg -o guest,sec=none,sec=ntlm
 
     mkdir -p /fs/proc
     mount -t proc none /fs/proc