diff --git a/flake.lock b/flake.lock
index ad5b6fc1..9e22d517 100644
--- a/flake.lock
+++ b/flake.lock
@@ -29,11 +29,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1753063383,
-        "narHash": "sha256-H+gLv6424OjJSD+l1OU1ejxkN/v0U+yaoQdh2huCXYI=",
+        "lastModified": 1757296493,
+        "narHash": "sha256-6nzSZl28IwH2Vx8YSmd3t6TREHpDbKlDPK+dq1LKIZQ=",
         "owner": "pyproject-nix",
         "repo": "build-system-pkgs",
-        "rev": "45888b7fd4bf36c57acc55f07917bdf49ec89ec9",
+        "rev": "5b8e37fe0077db5c1df3a5ee90a651345f085d38",
         "type": "github"
       },
       "original": {
@@ -49,11 +49,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1754287816,
-        "narHash": "sha256-kDt0HB89oWTlTQMnTwDxx3BlRHK1AdAJ1kMcVYGuccs=",
+        "lastModified": 1758087687,
+        "narHash": "sha256-mH17yoWmkT5Kf9cpbDp0s2pgU9iTnfadsypy4n5IXWY=",
         "owner": "pyproject-nix",
         "repo": "pyproject.nix",
-        "rev": "efe944d0902f406c28b4e8662312292a37e4de87",
+        "rev": "e82d2bf1b96908f457ef199fa69e97825d9f228f",
         "type": "github"
       },
       "original": {
@@ -80,11 +80,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1754285395,
-        "narHash": "sha256-ot8qz71k3Pqg/Fr6goQs3DCOz11IQEeSObuJ5LJOBPg=",
+        "lastModified": 1758104552,
+        "narHash": "sha256-v8h7NL8aNx1edzmCMQvJZ48rehZp3rzaIXuReF2x0vU=",
         "owner": "pyproject-nix",
         "repo": "uv2nix",
-        "rev": "0772521d8700b5cffb5420d14a085e92527f6fa2",
+        "rev": "8653cbebd61058e6629fc3ff79098775f9797df7",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index ba8e0ad7..dda68f9f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -38,7 +38,11 @@
     workspace = uv2nix.lib.workspace.loadWorkspace { workspaceRoot = ./.; };
 
     workspace-overlay = workspace.mkPyprojectOverlay {
-      sourcePreference = "wheel"; # or sourcePreference = "sdist";
+      sourcePreference = "wheel";
+    };
+
+    editable-overlay = workspace.mkEditablePyprojectOverlay {
+      root = "$REPO_ROOT";
     };
 
     pyproject-overlay = final: prev: {
@@ -56,6 +60,7 @@
       extensions = pkgs.lib.composeManyExtensions [
         pyproject-build-systems.overlays.default
         workspace-overlay
+        editable-overlay
         pyproject-overlay
       ];
       base-python = pkgs.callPackage pyproject-nix.build.packages {
@@ -82,6 +87,7 @@
         shellHook = ''
           # Undo dependency propagation by nixpkgs.
           unset PYTHONPATH
+          export REPO_ROOT=$(git rev-parse --show-toplevel)
         '';
         packages = [ python-env ] ++ (dev-tools pkgs);
       };