diff --git a/flake.nix b/flake.nix
index 336642ee..01e30c15 100644
--- a/flake.nix
+++ b/flake.nix
@@ -17,12 +17,30 @@
     // flake-utils.lib.eachDefaultSystem (
       system:
       let
+        lib = import "${nixpkgs}/lib";
+        inherit (self) lastModifiedDate;
+        year = lib.toIntBase10 (builtins.substring 0 4 lastModifiedDate);
+        month = lib.toIntBase10 (builtins.substring 4 2 lastModifiedDate);
+        day = lib.toIntBase10 (builtins.substring 6 2 lastModifiedDate);
         pkgs = import nixpkgs {
           inherit system;
           config = {
             allowAliases = false;
           };
-          overlays = [ self.overlays.default ];
+          overlays = [ self.overlays.default ] ++ lib.singleton (old: new: {
+            # This is here in flake.nix rather than common/packages/nix because it needs to access the flake metadata to get the date of the most recent commit (lastModifiedDate)
+            copyparty-unstable = new.copyparty.overrideAttrs (finalAttrs: previousAttrs: {
+              version = "${previousAttrs.version}-unstable-${self.lastModifiedDate}";
+              src = self;
+              postPatch = ''
+                old_src="$(mktemp -d)"
+                tar -C "$old_src" -xvf ${new.copyparty.src}
+                cp -r "$old_src"/*/copyparty/web/deps/* copyparty/web/deps
+                sed -i 's/^BUILD_DT =.*$/BUILD_DT = (${toString year}, ${toString month}, ${toString day})/' copyparty/__version__.py
+                sed -i 's/^CODENAME =.*$/CODENAME = "unstable"/' copyparty/__version__.py
+              '';
+            });
+          });
         };
       in
       {
@@ -42,6 +60,7 @@
         packages = {
           inherit (pkgs)
             copyparty
+            copyparty-unstable
             ;
           default = self.packages.${system}.copyparty;
         };