diff --git a/default.nix b/default.nix
index 0c9248a..35a779a 100644
--- a/default.nix
+++ b/default.nix
@@ -3,16 +3,8 @@
 # if evaluating inside the store, import the outputs.nix file
 
 let
-  contains = str: substr: let
-    str_length = builtins.stringLength str;
-    substr_length = builtins.stringLength substr;
-    listOfPossibleSubstrings = builtins.genList (i: builtins.substring i substr_length str) (str_length - substr_length + 1);
-  in if substr_length > str_length then false else builtins.any (x: x == substr) listOfPossibleSubstrings;
-
-  endsWith = str: substr: let
-    str_length = builtins.stringLength str;
-    substr_length = builtins.stringLength substr;
-  in if substr_length > str_length then false else builtins.substring (str_length - substr_length) str_length str == substr;
+  # Ideally this file should not depend on nixpkgs lib itself, but I like the utilities here
+  lib = (import "${(import ./inputs.nix {}).nixpkgs}/lib");
 
   gitignore = builtins.filter (v:
       # ignore comments and empty lines
@@ -32,11 +24,11 @@ let
       if pattern == "*" then true
       else if pattern == ".*" then true
       else if pattern == "*.*" then true
-      else if builtins.substring 0 2 pattern == "*." then endsWith path (builtins.substring 0 2 pattern)
-      else if contains pattern "*" then abort unsupportedPatternMessage
+      else if builtins.substring 0 2 pattern == "*." then lib.hasSuffix (builtins.substring 0 2 pattern) path
+      else if lib.hasInfix "*" pattern then abort unsupportedPatternMessage
       else if patternLength > 2 && builtins.substring 0 2 pattern == "./" then abort unsupportedPatternMessage
       else if patternLength > 1 && builtins.substring 0 1 pattern == "/" then abort unsupportedPatternMessage
-      else contains path pattern
+      else lib.hasInfix pattern path
   ) gitignore;
 
   currentFilePath = (builtins.unsafeGetAttrPos "any" { any = "any"; }).file;
diff --git a/inputs.nix b/inputs.nix
index 334379b..1979433 100644
--- a/inputs.nix
+++ b/inputs.nix
@@ -15,6 +15,11 @@ let self = {
     url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs.revision}.tar.gz";
     sha256 = "${lock.nixpkgs.sha256}";
   };
+  nixpkgs-unstable = builtins.fetchTarball {
+    name = "nixpkgs-unstable";
+    url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs-unstable.revision}.tar.gz";
+    sha256 = "${lock.nixpkgs-unstable.sha256}";
+  };
   cosmic-modules = builtins.fetchTarball {
     name = "cosmic-modules";
     url = "https://github.com/lilyinstarlight/nixos-cosmic/archive/${lock.cosmic-modules.revision}.tar.gz";
diff --git a/lib/overlays/version-info-fixup.nix b/lib/overlays/version-info-fixup.nix
index b413842..104840a 100644
--- a/lib/overlays/version-info-fixup.nix
+++ b/lib/overlays/version-info-fixup.nix
@@ -1,8 +1,8 @@
-{ inputs ? import ../../inputs.nix {} }:
+{ revision }:
 
 selfLib: superLib: {
   trivial = superLib.trivial // {
-    versionSuffix = ".git.${builtins.substring 0 12 inputs.lock.nixpkgs.revision}";
-    revisionWithDefault = default: inputs.lock.nixpkgs.revision or default;
+    versionSuffix = ".git.${builtins.substring 0 12 revision}";
+    revisionWithDefault = default: revision;
   };
 }
diff --git a/lock.nix b/lock.nix
index 100cf80..84cd166 100644
--- a/lock.nix
+++ b/lock.nix
@@ -7,6 +7,10 @@
     revision = "3f0a8ac25fb674611b98089ca3a5dd6480175751";
     sha256 = "10i7fllqjzq171afzhdf2d9r1pk9irvmq5n55h92rc47vlaabvr4";
   };
+  nixpkgs-unstable = {
+    revision = "130595eba61081acde9001f43de3248d8888ac4a";
+    sha256 = "0sw7zg4gal3wpz51ch1v36pdan9z73d4f3yrggh8h2clxs8jdgsx";
+  };
   cosmic-modules = {
     revision = "a934c861065b6b1aca9a859c45631336e0e8560c";
     sha256 = "1p0hs2z1h9fl25qvrlprf63cj1v0m7hr2y051mykjvdxikvn5a47";
diff --git a/nix-os/unstable-packages.nix b/nix-os/unstable-packages.nix
index 4c41240..b39d9f4 100644
--- a/nix-os/unstable-packages.nix
+++ b/nix-os/unstable-packages.nix
@@ -1,8 +1,14 @@
-{config, pkgs, lib, ...}:
+{
+  config,
+  lib,
+  pkgs,
+  self,
+  ...
+}:
 
 let
   cfg = config.unstable;
-  unstableOverlay = import ../pkgs/overlays/unstable.nix;
+  unstableOverlay = self.overlays.unstableWithMeta;
 in
 {
   options.unstable = {
diff --git a/outputs.nix b/outputs.nix
index 3355399..dd3f3ca 100644
--- a/outputs.nix
+++ b/outputs.nix
@@ -5,7 +5,7 @@
 
 let
 
-lib = (import "${inputs.nixpkgs}/lib").extend (import ./lib/overlays/version-info-fixup.nix { inherit inputs; });
+lib = (import "${inputs.nixpkgs}/lib").extend (import ./lib/overlays/version-info-fixup.nix { revision = inputs.lock.nixpkgs.revision; });
 
 self = {
   inherit inputs lib self;
@@ -15,7 +15,7 @@ self = {
   overlays = {
     cosmicPackages = import ./pkgs/overlays/cosmic-packages.nix { inherit inputs; };
     selfExpr = import ./pkgs/overlays/selfExpr.nix { nixpkgsPath = inputs.nixpkgs; };
-    unstable = import ./pkgs/overlays/unstable.nix;
+    unstableWithMeta = import ./pkgs/overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; };
     versionInfoFixup = import ./pkgs/overlays/version-info-fixup.nix { inherit inputs; };
   };
   nixosConfigurations = let
@@ -26,7 +26,7 @@ self = {
         ( # regular .nix files
           (type == "regular" && lib.hasSuffix ".nix" name)
           || # directories that contain a default.nix file
-          (type == "directory" && builtins.pathExists "${./hosts}/${name}/default.nix")
+          (type == "directory" && builtins.pathExists "${./.}/hosts/${name}/default.nix")
         )
         # filter out files that start with .
         && !lib.hasPrefix "." name
diff --git a/pkgs/overlays/unstable-with-meta.nix b/pkgs/overlays/unstable-with-meta.nix
new file mode 100644
index 0000000..dbfbc2c
--- /dev/null
+++ b/pkgs/overlays/unstable-with-meta.nix
@@ -0,0 +1,16 @@
+{
+  unstableSource,
+  revision,
+}: self: super:
+
+let
+  version = builtins.readFile "${unstableSource}/lib/.version" + ".git." + builtins.substring 0 12 revision;
+  useUnstable = self.config.useUnstable or true;
+
+in
+import ./unstable-from-source.nix {
+  inherit unstableSource;
+} self super // {
+  unstableVersion = self.lib.optionalString useUnstable version;
+  unstableRevision = self.lib.optionalString useUnstable revision;
+}
diff --git a/pkgs/overlays/unstable.nix b/pkgs/overlays/unstable.nix
deleted file mode 100644
index 73e79b9..0000000
--- a/pkgs/overlays/unstable.nix
+++ /dev/null
@@ -1,24 +0,0 @@
-self: super:
-
-let
-  nixos = self.config.nixos or true;
-  useUnstable = self.config.useUnstable or true;
-
-  unstablePkgsExprs = if nixos
-      then builtins.fetchTarball "https://channels.nixos.org/nixos-unstable/nixexprs.tar.xz"
-      else builtins.fetchTarball "https://channels.nixos.org/nixpkgs-unstable/nixexprs.tar.xz";
-
-  # Compiled nixpkgs expression eg expressions from a nix channel
-  nixpkgsVersion = builtins.concatStringsSep "." [
-    (builtins.readFile "${unstablePkgsExprs}/.version")
-    (builtins.readFile "${unstablePkgsExprs}/.version-suffix")
-  ];
-
-  nixpkgsRevision = (builtins.readFile "${unstablePkgsExprs}/.git-revision");
-in
-import ./unstable-from-source.nix {
-  unstableSource = unstablePkgsExprs;
-} self super // {
-  unstableVersion = self.lib.optionalString useUnstable nixpkgsVersion;
-  unstableRevision = self.lib.optionalString useUnstable nixpkgsRevision;
-}
diff --git a/pkgs/overlays/version-info-fixup.nix b/pkgs/overlays/version-info-fixup.nix
index 14d890e..b1f2ecc 100644
--- a/pkgs/overlays/version-info-fixup.nix
+++ b/pkgs/overlays/version-info-fixup.nix
@@ -1,5 +1,12 @@
 { inputs ? import ../../inputs.nix {} }:
 
 self: super: {
-  lib = super.lib.extend (import ../../lib/overlays/version-info-fixup.nix { inherit inputs; });
+  lib = super.lib.extend (import ../../lib/overlays/version-info-fixup.nix { revision = inputs.lock.nixpkgs.revision; });
+} //
+super.lib.optionalAttrs (super ? unstable && super ? unstableRevision) {
+  unstable = super.unstable // {
+    lib = super.unstable.lib.extend (import ../../lib/overlays/version-info-fixup.nix {
+      revision = super.unstableRevision;
+    });
+  };
 }
diff --git a/pkgs/top-level/default.nix b/pkgs/top-level/default.nix
index fd3e12a..dfdae8b 100644
--- a/pkgs/top-level/default.nix
+++ b/pkgs/top-level/default.nix
@@ -14,7 +14,7 @@ let
     overlays = (args.overlays or []) ++ [
       # ../.. should be nix store path that represents self in outputs.nix that is gc-rooted by this point
       ( import ../overlays/selfExpr.nix { nixpkgsPath = "${builtins.toString ../..}/pkgs/top-level/impure.nix"; } )
-      ( import ../overlays/unstable.nix )
+      ( import ../overlays/unstable-with-meta.nix { unstableSource = inputs.nixpkgs-unstable; revision = inputs.lock.nixpkgs-unstable.revision; } )
       ( import ../overlays/version-info-fixup.nix { inherit inputs; } )
       ( import ./by-name-overlay.nix ../by-name )
     ];