diff --git a/flake.nix b/flake.nix
index 16cac15..aab8aaf 100644
--- a/flake.nix
+++ b/flake.nix
@@ -7,9 +7,13 @@
   inputs.flake-utils.url = "github:numtide/flake-utils";
   inputs.flake-compat.url = "git+ssh://git@git.lix.systems/lix-project/flake-compat";
 
-  outputs = { self, nixpkgs, lix, flake-utils, ... }: {
+  outputs = inputs@{ self, nixpkgs, lix, flake-utils, ... }: {
+    inherit inputs;
     nixosModules.default = import ./module.nix { inherit lix; };
-    overlays.default = import ./overlay.nix { inherit lix; };
+    overlays.default = import ./overlay.nix {
+      inherit lix;
+      versionSuffix = "pre${builtins.substring 0 8 lix.lastModifiedDate}-${lix.shortRev}";
+    };
   } // flake-utils.lib.eachDefaultSystem (system:
     let
       pkgs = import nixpkgs {
diff --git a/overlay.nix b/overlay.nix
index 2d9f620..d526d5b 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -1,4 +1,4 @@
-{ lix }:
+{ lix, versionSuffix ? "" }:
 final: prev:
 let
   boehmgc-patched = ((final.boehmgc.override {
@@ -21,8 +21,8 @@ in
     nix_2_18 = (prev.nixVersions.nix_2_18.override { boehmgc = boehmgc-patched; }).overrideAttrs (old: {
       src = lix;
       # FIXME: fake version so that nixpkgs will not try to use nix config >_>
-      version = "2.18.3-lix";
-      VERSION_SUFFIX = "-lix";
+      version = "2.18.3-lix${versionSuffix}";
+      VERSION_SUFFIX = "-lix${versionSuffix}";
 
       patches = [ ];
       # FIXME: we don't know why this was not being picked up properly when