diff --git a/configuration.nix b/configuration.nix
index 5acb61c..f448212 100644
--- a/configuration.nix
+++ b/configuration.nix
@@ -8,6 +8,12 @@
   boot.loader.grub.enable = true;
   boot.loader.grub.device = "/dev/sda";  # REPLACE_ME with actual device
 
+  # Filesystem configuration (minimal placeholder for flake validation)
+  fileSystems."/" = {
+    device = "/dev/sda1";  # REPLACE_ME with actual device
+    fsType = "ext4";
+  };
+
   # Network configuration
   networking.useDHCP = false;
   networking.interfaces.eth0.useDHCP = true;  # REPLACE_ME with actual interface