diff --git a/pkgs/applications/networking/bee/bee-clef.nix b/pkgs/applications/networking/bee/bee-clef.nix
index a94386ea3f1..9e36f8670d4 100644
--- a/pkgs/applications/networking/bee/bee-clef.nix
+++ b/pkgs/applications/networking/bee/bee-clef.nix
@@ -1,4 +1,4 @@
-{ version ? "release", stdenv, lib, substituteAll, fetchFromGitHub, go-ethereum }:
+{ version ? "release", stdenv, lib, fetchFromGitHub, go-ethereum }:
 
 stdenv.mkDerivation rec {
   pname = "bee-clef";
diff --git a/pkgs/applications/networking/mumble/default.nix b/pkgs/applications/networking/mumble/default.nix
index 2eeb151bebe..4432d9ddeec 100644
--- a/pkgs/applications/networking/mumble/default.nix
+++ b/pkgs/applications/networking/mumble/default.nix
@@ -1,22 +1,15 @@
-{ lib, stdenv, fetchurl, fetchFromGitHub, fetchpatch, pkg-config, qt5
+{ lib, stdenv, fetchFromGitHub, pkg-config, qt5
 , avahi, boost, libopus, libsndfile, protobuf, speex, libcap
 , alsaLib, python3
 , rnnoise
-, jackSupport ? false, libjack2 ? null
-, speechdSupport ? false, speechd ? null
-, pulseSupport ? false, libpulseaudio ? null
-, iceSupport ? false, zeroc-ice ? null
-, grpcSupport ? false, grpc ? null, c-ares ? null, abseil-cpp ? null, which ? null
+, jackSupport ? false, libjack2
+, speechdSupport ? false, speechd
+, pulseSupport ? false, libpulseaudio
+, iceSupport ? false, zeroc-ice
+, grpcSupport ? false, grpc, c-ares, abseil-cpp, which
 , nixosTests
 }:
 
-assert jackSupport -> libjack2 != null;
-assert speechdSupport -> speechd != null;
-assert pulseSupport -> libpulseaudio != null;
-assert iceSupport -> zeroc-ice != null;
-assert grpcSupport -> (grpc != null && c-ares != null && abseil-cpp != null && which != null);
-
-with lib;
 let
   generic = overrides: source: qt5.mkDerivation (source // overrides // {
     pname = overrides.type;
@@ -42,8 +35,8 @@ let
       "CONFIG+=no-bundled-opus"
       "CONFIG+=no-bundled-speex"
       "DEFINES+=PLUGIN_PATH=${placeholder "out"}/lib/mumble"
-    ] ++ optional (!speechdSupport) "CONFIG+=no-speechd"
-      ++ optional jackSupport "CONFIG+=no-oss CONFIG+=no-alsa CONFIG+=jackaudio"
+    ] ++ lib.optional (!speechdSupport) "CONFIG+=no-speechd"
+      ++ lib.optional jackSupport "CONFIG+=no-oss CONFIG+=no-alsa CONFIG+=jackaudio"
       ++ (overrides.configureFlags or [ ]);
 
     preConfigure = ''
@@ -64,11 +57,9 @@ let
       runHook postInstall
     '';
 
-    enableParallelBuilding = true;
-
     passthru.tests.connectivity = nixosTests.mumble;
 
-    meta = {
+    meta = with lib; {
       description = "Low-latency, high quality voice chat software";
       homepage = "https://mumble.info";
       license = licenses.bsd3;
@@ -82,16 +73,16 @@ let
 
     nativeBuildInputs = [ qt5.qttools ];
     buildInputs = [ libopus libsndfile speex qt5.qtsvg rnnoise ]
-      ++ optional stdenv.isLinux alsaLib
-      ++ optional jackSupport libjack2
-      ++ optional speechdSupport speechd
-      ++ optional pulseSupport libpulseaudio;
+      ++ lib.optional stdenv.isLinux alsaLib
+      ++ lib.optional jackSupport libjack2
+      ++ lib.optional speechdSupport speechd
+      ++ lib.optional pulseSupport libpulseaudio;
 
     configureFlags = [
       "CONFIG+=no-server"
     ];
 
-    NIX_CFLAGS_COMPILE = optional speechdSupport "-I${speechd}/include/speech-dispatcher";
+    NIX_CFLAGS_COMPILE = lib.optional speechdSupport "-I${speechd}/include/speech-dispatcher";
 
     installPhase = ''
       # bin stuff
@@ -113,18 +104,18 @@ let
   server = source: generic {
     type = "murmur";
 
-    postPatch = optional iceSupport ''
+    postPatch = lib.optional iceSupport ''
       grep -Rl '/usr/share/Ice' . | xargs sed -i 's,/usr/share/Ice/,${zeroc-ice.dev}/share/ice/,g'
     '';
 
     configureFlags = [
       "CONFIG+=no-client"
-    ] ++ optional (!iceSupport) "CONFIG+=no-ice"
-      ++ optional grpcSupport "CONFIG+=grpc";
+    ] ++ lib.optional (!iceSupport) "CONFIG+=no-ice"
+      ++ lib.optional grpcSupport "CONFIG+=grpc";
 
     buildInputs = [ libcap ]
-      ++ optional iceSupport zeroc-ice
-      ++ optionals grpcSupport [ grpc c-ares abseil-cpp which ];
+      ++ lib.optional iceSupport zeroc-ice
+      ++ lib.optionals grpcSupport [ grpc c-ares abseil-cpp which ];
 
     installPhase = ''
       # bin stuff
diff --git a/pkgs/development/python-modules/aiobotocore/default.nix b/pkgs/development/python-modules/aiobotocore/default.nix
index 2e7c9c2401c..5d9c3fe1669 100644
--- a/pkgs/development/python-modules/aiobotocore/default.nix
+++ b/pkgs/development/python-modules/aiobotocore/default.nix
@@ -1,10 +1,7 @@
 { lib
-
 , buildPythonPackage
 , fetchPypi
 , pythonOlder
-, pytestrunner
-, typing-extensions
 , wrapt
 , aioitertools
 , aiohttp
diff --git a/pkgs/development/python-modules/botocore/default.nix b/pkgs/development/python-modules/botocore/default.nix
index 065d4409ec1..635203f94c2 100644
--- a/pkgs/development/python-modules/botocore/default.nix
+++ b/pkgs/development/python-modules/botocore/default.nix
@@ -28,10 +28,6 @@ buildPythonPackage rec {
     urllib3
   ];
 
-  postPatch = ''
-    substituteInPlace setup.py --replace "docutils>=0.10,<0.16" "docutils>=0.10"
-  '';
-
   checkInputs = [ mock nose ];
 
   checkPhase = ''
diff --git a/pkgs/development/python-modules/chalice/default.nix b/pkgs/development/python-modules/chalice/default.nix
index 5445157b853..9115b1d57c3 100644
--- a/pkgs/development/python-modules/chalice/default.nix
+++ b/pkgs/development/python-modules/chalice/default.nix
@@ -52,8 +52,7 @@ buildPythonPackage rec {
   postPatch = ''
     sed -i setup.py -e "/pip>=/c\'pip',"
     substituteInPlace setup.py \
-      --replace 'typing==3.6.4' 'typing' \
-      --replace 'attrs>=19.3.0,<20.3.0' 'attrs'
+      --replace 'typing==3.6.4' 'typing'
   '';
 
   checkPhase = ''
diff --git a/pkgs/development/python-modules/kombu/default.nix b/pkgs/development/python-modules/kombu/default.nix
index 1aa22a62e19..a5ca1a7ab2a 100644
--- a/pkgs/development/python-modules/kombu/default.nix
+++ b/pkgs/development/python-modules/kombu/default.nix
@@ -22,8 +22,6 @@ buildPythonPackage rec {
   postPatch = ''
     substituteInPlace requirements/test.txt \
       --replace "pytest-sugar" ""
-    substituteInPlace requirements/default.txt \
-      --replace "amqp==2.5.1" "amqp~=2.5"
   '';
 
   propagatedBuildInputs = [
diff --git a/pkgs/development/python-modules/pecan/default.nix b/pkgs/development/python-modules/pecan/default.nix
index a66c4077c3c..50b62503ff8 100644
--- a/pkgs/development/python-modules/pecan/default.nix
+++ b/pkgs/development/python-modules/pecan/default.nix
@@ -16,7 +16,6 @@
 , Kajiki
 , mock
 , sqlalchemy
-, uwsgi
 , virtualenv
 }:
 
diff --git a/pkgs/development/python-modules/serverlessrepo/default.nix b/pkgs/development/python-modules/serverlessrepo/default.nix
index 1e6f8307fbc..2a8267710a0 100644
--- a/pkgs/development/python-modules/serverlessrepo/default.nix
+++ b/pkgs/development/python-modules/serverlessrepo/default.nix
@@ -29,10 +29,6 @@ buildPythonPackage rec {
     pytest tests/unit
   '';
 
-  postPatch = ''
-    substituteInPlace setup.py --replace "pyyaml~=3.12" "pyyaml~=5.1"
-  '';
-
   meta = with lib; {
     homepage = "https://github.com/awslabs/aws-serverlessrepo-python";
     description = "Helpers for working with the AWS Serverless Application Repository";
diff --git a/pkgs/development/python-modules/shapely/default.nix b/pkgs/development/python-modules/shapely/default.nix
index b5875818b95..91c34734a8c 100644
--- a/pkgs/development/python-modules/shapely/default.nix
+++ b/pkgs/development/python-modules/shapely/default.nix
@@ -1,5 +1,5 @@
 { lib, stdenv, buildPythonPackage, fetchPypi, fetchpatch, substituteAll, pythonOlder
-, geos, pytest, cython
+, geos, pytestCheckHook, cython
 , numpy
 }:
 
@@ -18,10 +18,10 @@ buildPythonPackage rec {
     cython
   ];
 
-  checkInputs = [ pytest ];
-
   propagatedBuildInputs = [ numpy ];
 
+  checkInputs = [ pytestCheckHook ];
+
   # environment variable used in shapely/_buildcfg.py
   GEOS_LIBRARY_PATH = "${geos}/lib/libgeos_c${stdenv.hostPlatform.extensions.sharedLibrary}";
 
@@ -38,12 +38,14 @@ buildPythonPackage rec {
    })
  ];
 
-  # Disable the tests that improperly try to use the built extensions
-  checkPhase = ''
+  preCheck = ''
     rm -r shapely # prevent import of local shapely
-    py.test tests
   '';
 
+  disabledTests = [
+    "test_collection"
+  ];
+
   meta = with lib; {
     description = "Geometric objects, predicates, and operations";
     maintainers = with maintainers; [ knedlsepp ];
diff --git a/pkgs/development/python-modules/smart_open/default.nix b/pkgs/development/python-modules/smart_open/default.nix
index 3a1c890f048..389feef2b42 100644
--- a/pkgs/development/python-modules/smart_open/default.nix
+++ b/pkgs/development/python-modules/smart_open/default.nix
@@ -21,11 +21,6 @@ buildPythonPackage rec {
     sha256 = "26af5c1a3f2b76aab8c3200310f0fc783790ec5a231ffeec102e620acdd6262e";
   };
 
-  # nixpkgs version of moto is >=1.2.0, remove version pin to fix build
-  postPatch = ''
-    substituteInPlace ./setup.py --replace "moto==0.4.31" "moto"
-  '';
-
   # moto>=1.0.0 is backwards-incompatible and some tests fail with it,
   # so disable tests for now
   doCheck = false;
diff --git a/pkgs/servers/rippled/default.nix b/pkgs/servers/rippled/default.nix
index 22223f2a27e..cd19c77cab3 100644
--- a/pkgs/servers/rippled/default.nix
+++ b/pkgs/servers/rippled/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchFromGitHub, fetchgit, fetchurl, runCommand, git, cmake, pkg-config
+{ lib, stdenv, fetchgit, fetchurl, git, cmake, pkg-config
 , openssl,  zlib, boost, grpc, c-ares, abseil-cpp, protobuf3_8, libnsl }:
 
 let
diff --git a/pkgs/tools/admin/aws-mfa/default.nix b/pkgs/tools/admin/aws-mfa/default.nix
index 12f63e627e6..53855b6d28d 100644
--- a/pkgs/tools/admin/aws-mfa/default.nix
+++ b/pkgs/tools/admin/aws-mfa/default.nix
@@ -1,7 +1,6 @@
 { lib
 , buildPythonApplication
 , fetchFromGitHub
-, pkgs
 , boto3
 }:
 
diff --git a/pkgs/tools/backup/btrbk/default.nix b/pkgs/tools/backup/btrbk/default.nix
index 63808d48512..c619a69c111 100644
--- a/pkgs/tools/backup/btrbk/default.nix
+++ b/pkgs/tools/backup/btrbk/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, coreutils, bash, btrfs-progs, openssh, perl, perlPackages
+{ lib, stdenv, fetchurl, bash, btrfs-progs, openssh, perl, perlPackages
 , util-linux, asciidoc, asciidoctor, mbuffer, makeWrapper }:
 
 stdenv.mkDerivation rec {