diff --git a/default.nix b/default.nix
index bcdae155f..e180a6f38 100644
--- a/default.nix
+++ b/default.nix
@@ -77,7 +77,7 @@ let
     "-f dev --test-show-detail=direct";
 
   profiledHaskellPackages =
-    pkgs.haskell.packages."${compiler}".extend (self: super:
+    pkgs.haskell.packages."${compiler}".extend (_: super:
       {
         mkDerivation =
           args:
@@ -118,7 +118,7 @@ rec {
     pkgs.callPackage nix/tools/cabalTools.nix { inherit devCabalOptions postgrest; };
 
   withTools =
-    pkgs.callPackage nix/tools/withTools.nix { inherit cabalTools devCabalOptions postgresqlVersions postgrest; };
+    pkgs.callPackage nix/tools/withTools.nix { inherit postgresqlVersions postgrest; };
 
   # Development tools.
   devTools =
diff --git a/nix/libpq.nix b/nix/libpq.nix
index 63542611e..ca9103baf 100644
--- a/nix/libpq.nix
+++ b/nix/libpq.nix
@@ -11,7 +11,6 @@
 , openssl
 , zlib
 , libkrb5
-, icu
 , postgresql
 , pkg-config
 , tzdata
diff --git a/nix/overlays/build-toolbox/default.nix b/nix/overlays/build-toolbox/default.nix
index 201b2e953..79a664189 100644
--- a/nix/overlays/build-toolbox/default.nix
+++ b/nix/overlays/build-toolbox/default.nix
@@ -1,4 +1,4 @@
-self: super:
+_: super:
 # Overlay that adds `buildToolbox`, an enhanced version of `buildEnv`
 {
   buildToolbox = super.callPackage ./build-toolbox.nix { };
diff --git a/nix/overlays/checked-shell-script/default.nix b/nix/overlays/checked-shell-script/default.nix
index c8a16633d..b1766aa00 100644
--- a/nix/overlays/checked-shell-script/default.nix
+++ b/nix/overlays/checked-shell-script/default.nix
@@ -1,4 +1,4 @@
-self: super:
+_: super:
 # Overlay that adds `checkedShellScript`, an enhanced version of
 # writeShellScript and writeShellScriptBin
 {
diff --git a/nix/overlays/gitignore.nix b/nix/overlays/gitignore.nix
index 7c8342c89..0e6aa283f 100644
--- a/nix/overlays/gitignore.nix
+++ b/nix/overlays/gitignore.nix
@@ -1,4 +1,4 @@
-self: super:
+_: super:
 # Overlay that adds the `gitignoreSource` function from Hercules-CI.
 # This function is useful for filtering which files are added to the Nix store.
 # See: https://github.com/hercules-ci/gitignore.nix
diff --git a/nix/overlays/haskell-packages.nix b/nix/overlays/haskell-packages.nix
index b8515170f..16a25bf0f 100644
--- a/nix/overlays/haskell-packages.nix
+++ b/nix/overlays/haskell-packages.nix
@@ -5,7 +5,7 @@ let
   inherit (self.haskell) lib;
 
   overrides =
-    final: prev:
+    _: prev:
     rec {
       # To pin custom versions of Haskell packages:
       #   protolude =
diff --git a/nix/overlays/postgresql-future.nix b/nix/overlays/postgresql-future.nix
index 90964d075..5ef8a42d8 100644
--- a/nix/overlays/postgresql-future.nix
+++ b/nix/overlays/postgresql-future.nix
@@ -1,4 +1,4 @@
-self: super:
+_: _:
 # Overlay that adds future versions of PostgreSQL that are supported by
 # PostgREST.
 {
diff --git a/nix/overlays/postgresql-legacy.nix b/nix/overlays/postgresql-legacy.nix
index cd07af5aa..506d8eb34 100644
--- a/nix/overlays/postgresql-legacy.nix
+++ b/nix/overlays/postgresql-legacy.nix
@@ -1,4 +1,4 @@
-self: super:
+_: _:
 # Overlay that adds legacy versions of PostgreSQL that are supported by
 # PostgREST.
 {
diff --git a/nix/overlays/postgresql-libpq.nix b/nix/overlays/postgresql-libpq.nix
index 5f342bd86..2d1841e60 100644
--- a/nix/overlays/postgresql-libpq.nix
+++ b/nix/overlays/postgresql-libpq.nix
@@ -1,4 +1,4 @@
-self: super:
+_: super:
 {
   libpq = super.callPackage ../libpq.nix {
     postgresql = super.postgresql_16;
diff --git a/nix/overlays/slocat.nix b/nix/overlays/slocat.nix
index 577b527fb..f26d71a39 100644
--- a/nix/overlays/slocat.nix
+++ b/nix/overlays/slocat.nix
@@ -1,4 +1,4 @@
-final: prev:
+_: prev:
 {
   slocat = prev.buildGoModule {
     name = "slocat";
diff --git a/nix/static.nix b/nix/static.nix
index ca13564c8..76387a321 100644
--- a/nix/static.nix
+++ b/nix/static.nix
@@ -23,12 +23,12 @@ let
         enableNativeBignum = true;
       };
 
-      overrides = pkgs.lib.composeExtensions old.overrides (final: prev: {
+      overrides = pkgs.lib.composeExtensions old.overrides (_: prev: {
         postgresql-libpq = (prev.postgresql-libpq.override {
           # postgresql doesn't build in the fully static overlay - but the default
           # derivation is built with static libraries anyway.
           postgresql = pkgsCross.libpq;
-        }).overrideAttrs (finalAttrs: prevAttrs: {
+        }).overrideAttrs (_: prevAttrs: {
           # Using use-pkg-config flag, because pg_config won't work when cross-compiling
           configureFlags = prevAttrs.configureFlags ++ [
             "-fuse-pkg-config"
@@ -38,7 +38,7 @@ let
           nativeBuildInputs = prevAttrs.nativeBuildInputs ++ [ pkgsCross.pkgsBuildHost.pkg-config ];
 
           buildInputs = prevAttrs.buildInputs ++ [
-            (pkgsStatic.libkrb5.overrideAttrs (finalAttrs: prevAttrs: {
+            (pkgsStatic.libkrb5.overrideAttrs (_: prevAttrs: {
               configureFlags = prevAttrs.configureFlags ++ [
                 "--sysconfdir=/etc"
                 # disable keyutils dependency, to avoid linking errors
diff --git a/nix/tools/devTools.nix b/nix/tools/devTools.nix
index d2b0a9ac4..5c9ed0e40 100644
--- a/nix/tools/devTools.nix
+++ b/nix/tools/devTools.nix
@@ -5,9 +5,7 @@
 , devCabalOptions
 , entr
 , git
-, gnugrep
 , graphviz
-, haskellPackages
 , hsie
 , nix
 , silver-searcher
diff --git a/nix/tools/style.nix b/nix/tools/style.nix
index 1ad91041c..4738868d9 100644
--- a/nix/tools/style.nix
+++ b/nix/tools/style.nix
@@ -2,6 +2,7 @@
 , black
 , buildToolbox
 , checkedShellScript
+, deadnix
 , git
 , hlint
 , hsie
@@ -65,10 +66,12 @@ let
         echo "Linting workflows..."
         ${actionlint}/bin/actionlint
 
+        echo "Scanning nix files for unused code..."
+        ${deadnix}/bin/deadnix
+
         echo "Checking consistency of import aliases in Haskell code..."
         ${hsie} check-aliases main src
 
-
         echo "Linting Haskell files..."
         # --vimgrep fixes a bug in ag: https://github.com/ggreer/the_silver_searcher/issues/753
         ${silver-searcher}/bin/ag -l --vimgrep -g '\.l?hs$' . \
diff --git a/nix/tools/withTools.nix b/nix/tools/withTools.nix
index e5c32e690..57e27476e 100644
--- a/nix/tools/withTools.nix
+++ b/nix/tools/withTools.nix
@@ -1,10 +1,6 @@
-{ bash-completion
-, buildToolbox
-, cabal-install
-, cabalTools
+{ buildToolbox
 , checkedShellScript
 , curl
-, devCabalOptions
 , git
 , lib
 , postgresqlVersions
@@ -276,30 +272,6 @@ let
         log-level="$(PGRST_LOG_LEVEL)"
       '';
 
-  waitForPgrstPid =
-    checkedShellScript
-      {
-        name = "postgrest-wait-for-pgrst-pid";
-        docs = "Wait for PostgREST to be running. Needs to be a separate command for timeout to work below.";
-        args = [
-          "ARG_USE_ENV([PGRST_SERVER_UNIX_SOCKET], [], [Unix socket to check for running PostgREST instance])"
-        ];
-      }
-      ''
-        # ARG_USE_ENV only adds defaults or docs for environment variables
-        # We manually implement a required check here
-        # See also: https://github.com/matejak/argbash/issues/80
-        : "''${PGRST_SERVER_UNIX_SOCKET:?PGRST_SERVER_UNIX_SOCKET is required}"
-
-        until [ -S "$PGRST_SERVER_UNIX_SOCKET" ]
-        do
-          sleep 0.1
-        done
-
-        # return pid of postgrest process
-        lsof -t -c '/^postgrest$/' "$PGRST_SERVER_UNIX_SOCKET"
-      '';
-
   waitForPgrstReady =
     checkedShellScript
       {