diff --git a/nixos/modules/virtualisation/virtualbox-image.nix b/nixos/modules/virtualisation/virtualbox-image.nix
index 037c0d2f0d8..903411799d3 100644
--- a/nixos/modules/virtualisation/virtualbox-image.nix
+++ b/nixos/modules/virtualisation/virtualbox-image.nix
@@ -94,6 +94,7 @@ in {
     fileSystems."/" = {
       device = "/dev/disk/by-label/nixos";
       autoResize = true;
+      fsType = "ext4";
     };
 
     boot.growPartition = true;