diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0721186..7b268c7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,9 @@ jobs:
   nixpkgs-fmt:
     runs-on: ubuntu-latest
     steps:
-    - uses: cachix/install-nix-action@v12
+    - uses: cachix/install-nix-action@v13
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
     - uses: actions/checkout@v1
     - name: Check format
       run: ./check-fmt
@@ -22,10 +24,12 @@ jobs:
         os: [ubuntu-latest]
         # os: [ubuntu-latest, macos-latest]
     steps:
-    - uses: cachix/install-nix-action@v12
+    - uses: cachix/install-nix-action@v13
+      with:
+        nix_path: nixpkgs=channel:nixos-unstable
     - uses: actions/checkout@v1
     - uses: cachix/cachix-action@v8
       with:
         name: poetry2nix
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
-    - run: nix-build --keep-going --show-trace tests/default.nix
+    - run: nix-shell -p nix-build-uncached --run 'nix-build-uncached --keep-going --show-trace tests/default.nix'
diff --git a/tests/git-deps-pinned/poetry-git-overlay.nix b/tests/git-deps-pinned/poetry-git-overlay.nix
index 62537b6..8c9c86b 100644
--- a/tests/git-deps-pinned/poetry-git-overlay.nix
+++ b/tests/git-deps-pinned/poetry-git-overlay.nix
@@ -1,7 +1,7 @@
 { pkgs }:
 self: super: {
 
-  alembic = super.alembic.overrideAttrs (
+  alembic = super.alembic.overridePythonAttrs (
     _: {
       src = pkgs.fetchgit {
         url = "https://github.com/sqlalchemy/alembic.git";
@@ -11,4 +11,24 @@ self: super: {
     }
   );
 
+  colorama = super.colorama.overridePythonAttrs (
+    _: {
+      src = pkgs.fetchgit {
+        url = "https://github.com/tartley/colorama.git";
+        rev = "4321bbfda9aa190acdad05eb901d3b59439f0ec9";
+        sha256 = "1z88yl4r4g6yv29rw0q7zwylgx9zss360n3s9v07macvv50cb452";
+      };
+    }
+  );
+
+  s3transfer = super.s3transfer.overridePythonAttrs (
+    _: {
+      src = pkgs.fetchgit {
+        url = "https://github.com/boto/s3transfer.git";
+        rev = "b2b6c44cb283e134f6bf9fecad7ff5ee28df793d";
+        sha256 = "1dzjzfxp9rkrh1s6ic22kwmr00hqrgz0da330vydlfpmcqgyp1fy";
+      };
+    }
+  );
+
 }