diff --git a/pkgs/by-name/cp/cp2k/package.nix b/pkgs/by-name/cp/cp2k/package.nix
index dec5d5510ff1..69c6777c9fc6 100644
--- a/pkgs/by-name/cp/cp2k/package.nix
+++ b/pkgs/by-name/cp/cp2k/package.nix
@@ -70,7 +70,7 @@ let
   grimmeCmake = lib.makeScope newScope (self: {
     mctc-lib = mctc-lib.override {
       buildType = "cmake";
-      inherit (self) jonquil toml-f;
+      inherit (self) jonquil;
     };
 
     toml-f = toml-f.override {
diff --git a/pkgs/by-name/df/dftd4/package.nix b/pkgs/by-name/df/dftd4/package.nix
index e77583857422..b05d1214d5a4 100644
--- a/pkgs/by-name/df/dftd4/package.nix
+++ b/pkgs/by-name/df/dftd4/package.nix
@@ -2,7 +2,6 @@
   stdenv,
   lib,
   fetchFromGitHub,
-  fetchpatch,
   gfortran,
   buildType ? "meson",
   cmake,
diff --git a/pkgs/by-name/mc/mctc-lib/package.nix b/pkgs/by-name/mc/mctc-lib/package.nix
index 96e2f68dadb5..6883ac8a7e6a 100644
--- a/pkgs/by-name/mc/mctc-lib/package.nix
+++ b/pkgs/by-name/mc/mctc-lib/package.nix
@@ -9,7 +9,6 @@
   cmake,
   pkg-config,
   python3,
-  toml-f,
   jonquil,
 }:
 
@@ -62,6 +61,10 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
+  preCheck = ''
+    export OMP_NUM_THREADS=2
+  '';
+
   postPatch = ''
     patchShebangs --build config/install-mod.py
   '';
diff --git a/pkgs/by-name/si/sirius/package.nix b/pkgs/by-name/si/sirius/package.nix
index a7636abc3483..f0b404de0de6 100644
--- a/pkgs/by-name/si/sirius/package.nix
+++ b/pkgs/by-name/si/sirius/package.nix
@@ -51,7 +51,7 @@ assert builtins.elem gpuBackend [
 ];
 assert enablePython -> pythonPackages != null;
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation {
   pname = "SIRIUS";
   version = "7.8.0-unstable-2025-07-23";
 
diff --git a/pkgs/development/libraries/science/chemistry/tblite/python.nix b/pkgs/development/libraries/science/chemistry/tblite/python.nix
index 09f921cc4ae7..5fa76765a655 100644
--- a/pkgs/development/libraries/science/chemistry/tblite/python.nix
+++ b/pkgs/development/libraries/science/chemistry/tblite/python.nix
@@ -1,5 +1,4 @@
 {
-  lib,
   buildPythonPackage,
   meson,
   ninja,