diff --git a/flake.nix b/flake.nix
index 7d8ff0d8f..83d70d3e0 100644
--- a/flake.nix
+++ b/flake.nix
@@ -391,17 +391,20 @@
           '';
 
       overlayFor = getStdenv: final: prev:
-        let currentStdenv = getStdenv final; in
-        {
-          nixStable = prev.nix;
-
-          nix =
-          with final;
-          with commonDeps {
+        let
+          currentStdenv = getStdenv final;
+          comDeps = with final; commonDeps {
             inherit pkgs;
             inherit (currentStdenv.hostPlatform) isStatic;
           };
-          let
+          inherit (final) stdenv boost;
+        in {
+          nixStable = prev.nix;
+
+          # Forward from the previous stage as we don’t want it to pick the lowdown override
+          nixUnstable = prev.nixUnstable;
+
+          nix = let
             canRunInstalled = currentStdenv.buildPlatform.canExecute currentStdenv.hostPlatform;
           in currentStdenv.mkDerivation (finalAttrs: {
             name = "nix-${version}";
@@ -412,13 +415,13 @@
 
             outputs = [ "out" "dev" "doc" ];
 
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps
+            nativeBuildInputs = comDeps.nativeBuildDeps;
+            buildInputs = comDeps.buildDeps
               # There have been issues building these dependencies
-              ++ lib.optionals (currentStdenv.hostPlatform == currentStdenv.buildPlatform) awsDeps
-              ++ lib.optionals finalAttrs.doCheck checkDeps;
+              ++ lib.optionals (currentStdenv.hostPlatform == currentStdenv.buildPlatform) comDeps.awsDeps
+              ++ lib.optionals finalAttrs.doCheck comDeps.checkDeps;
 
-            propagatedBuildInputs = propagatedDeps;
+            propagatedBuildInputs = comDeps.propagatedDeps;
 
             disallowedReferences = [ boost ];
 
@@ -443,11 +446,11 @@
                 ''}
               '';
 
-            configureFlags = configureFlags ++
+            configureFlags = comDeps.configureFlags ++
               [ "--sysconfdir=/etc" ] ++
               lib.optional stdenv.hostPlatform.isStatic "--enable-embedded-sandbox-shell" ++
               [ (lib.enableFeature finalAttrs.doCheck "tests") ] ++
-              lib.optionals finalAttrs.doCheck testConfigureFlags ++
+              lib.optionals finalAttrs.doCheck comDeps.testConfigureFlags ++
               lib.optional (!canRunInstalled) "--disable-doc-gen";
 
             enableParallelBuilding = true;