diff --git a/pkgs/applications/misc/qsyncthingtray/default.nix b/pkgs/applications/misc/qsyncthingtray/default.nix
index cdb4f603821..100be6c2dc8 100644
--- a/pkgs/applications/misc/qsyncthingtray/default.nix
+++ b/pkgs/applications/misc/qsyncthingtray/default.nix
@@ -67,6 +67,6 @@ mkDerivation rec {
     # 0.5.7 segfaults when opening the main panel with qt 5.7 and fails to compile with qt 5.8
     # but qt > 5.6 works when only using the native browser
     # https://github.com/sieren/QSyncthingTray/issues/223
-    broken = (builtins.compareVersions qtbase.version "5.7.0" >= 0 && !preferNative);
+    broken = (builtins.compareVersions qtbase.version "5.7.0" >= 0 && !preferNative) || stdenv.isDarwin;
   };
 }
diff --git a/pkgs/applications/networking/cluster/k3s/default.nix b/pkgs/applications/networking/cluster/k3s/default.nix
index 5a7d953a069..739992e6bc0 100644
--- a/pkgs/applications/networking/cluster/k3s/default.nix
+++ b/pkgs/applications/networking/cluster/k3s/default.nix
@@ -120,7 +120,7 @@ let
   # with generated bindata yet.
   k3sBuildStage1 = buildGoPackage rec {
     name = "k3s-build-1";
-    version = "${k3sVersion}";
+    version = k3sVersion;
 
     goPackagePath = "github.com/rancher/k3s";
 
@@ -160,7 +160,7 @@ let
   };
   k3sBin = buildGoPackage rec {
     name = "k3s-bin";
-    version = "${k3sVersion}";
+    version = k3sVersion;
 
     goPackagePath = "github.com/rancher/k3s";
 
diff --git a/pkgs/applications/networking/gns3/server.nix b/pkgs/applications/networking/gns3/server.nix
index 62fdfd71f23..5ba6b57d5bd 100644
--- a/pkgs/applications/networking/gns3/server.nix
+++ b/pkgs/applications/networking/gns3/server.nix
@@ -34,10 +34,8 @@ in python.pkgs.buildPythonPackage {
   };
 
   postPatch = ''
-    # yarl 1.4+ only requires Python 3.6+
     substituteInPlace requirements.txt \
-      --replace "aiohttp==3.6.2" "aiohttp>=3.6.2" \
-      --replace "yarl==1.3.0" ""
+      --replace "aiohttp==3.6.2" "aiohttp>=3.6.2"
   '';
 
   propagatedBuildInputs = with python.pkgs; [
diff --git a/pkgs/applications/networking/protonvpn-gui/default.nix b/pkgs/applications/networking/protonvpn-gui/default.nix
index c2d7fbd10b1..8029264fdaa 100644
--- a/pkgs/applications/networking/protonvpn-gui/default.nix
+++ b/pkgs/applications/networking/protonvpn-gui/default.nix
@@ -76,6 +76,9 @@ in python3Packages.buildPythonApplication rec {
     done
   '';
 
+  # no tests
+  doCheck = false;
+
   meta = with lib; {
     description = "Linux GUI for ProtonVPN, written in Python";
     homepage = "https://github.com/ProtonVPN/linux-gui";
diff --git a/pkgs/applications/version-management/git-and-tools/git-interactive-rebase-tool/default.nix b/pkgs/applications/version-management/git-and-tools/git-interactive-rebase-tool/default.nix
index 376568324b7..f28d49702bc 100644
--- a/pkgs/applications/version-management/git-and-tools/git-interactive-rebase-tool/default.nix
+++ b/pkgs/applications/version-management/git-and-tools/git-interactive-rebase-tool/default.nix
@@ -23,6 +23,6 @@ rustPlatform.buildRustPackage rec {
     description = "Native cross platform full feature terminal based sequence editor for git interactive rebase";
     changelog = "https://github.com/MitMaro/git-interactive-rebase-tool/releases/tag/${version}";
     license = licenses.mit;
-    maintainers = with maintainers; [ masaeedu zowoq ];
+    maintainers = with maintainers; [ masaeedu SuperSandro2000 zowoq ];
   };
 }
diff --git a/pkgs/development/python-modules/datashader/default.nix b/pkgs/development/python-modules/datashader/default.nix
index c49e2e30b80..534cc816def 100644
--- a/pkgs/development/python-modules/datashader/default.nix
+++ b/pkgs/development/python-modules/datashader/default.nix
@@ -76,11 +76,6 @@ buildPythonPackage rec {
     nbconvert
   ];
 
-  postConfigure = ''
-    substituteInPlace setup.py \
-      --replace "'numba >=0.37.0,<0.49'" "'numba'"
-  '';
-
   # dask doesn't do well with large core counts
   checkPhase = ''
     pytest -n $NIX_BUILD_CORES datashader -k 'not dask.array'
diff --git a/pkgs/development/python-modules/j2cli/default.nix b/pkgs/development/python-modules/j2cli/default.nix
index d6efe84edfd..c83b1c77e2c 100644
--- a/pkgs/development/python-modules/j2cli/default.nix
+++ b/pkgs/development/python-modules/j2cli/default.nix
@@ -26,7 +26,7 @@ buildPythonPackage rec {
       J2Cli is a command-line tool for templating in shell-scripts,
       leveraging the Jinja2 library.
     '';
-    maintainers = with maintainers; [ rushmorem ];
+    maintainers = with maintainers; [ rushmorem SuperSandro2000 ];
   };
 
 }
diff --git a/pkgs/development/python-modules/jupyterhub-systemdspawner/default.nix b/pkgs/development/python-modules/jupyterhub-systemdspawner/default.nix
index 71fba8a1222..bd3e073a772 100644
--- a/pkgs/development/python-modules/jupyterhub-systemdspawner/default.nix
+++ b/pkgs/development/python-modules/jupyterhub-systemdspawner/default.nix
@@ -28,6 +28,9 @@ buildPythonPackage rec {
       --replace "/bin/bash" "${bash}/bin/bash"
   '';
 
+  # no tests
+  doCheck = false;
+
   meta = with lib; {
     description = "JupyterHub Spawner using systemd for resource isolation";
     homepage = "https://github.com/jupyterhub/systemdspawner";
diff --git a/pkgs/development/python-modules/slackclient/default.nix b/pkgs/development/python-modules/slackclient/default.nix
index a690788095e..d990295bff6 100644
--- a/pkgs/development/python-modules/slackclient/default.nix
+++ b/pkgs/development/python-modules/slackclient/default.nix
@@ -49,6 +49,8 @@ buildPythonPackage rec {
     responses
   ];
 
+  pythonImportsCheck = [ "slack" ];
+
   meta = with lib; {
     description = "A client for Slack, which supports the Slack Web API and Real Time Messaging (RTM) API";
     homepage = "https://github.com/slackapi/python-slackclient";
diff --git a/pkgs/tools/misc/duf/default.nix b/pkgs/tools/misc/duf/default.nix
index ed8a11e182c..82cc7fa29e4 100644
--- a/pkgs/tools/misc/duf/default.nix
+++ b/pkgs/tools/misc/duf/default.nix
@@ -2,26 +2,24 @@
 
 buildGoModule rec {
   pname = "duf";
-  version = "0.5.0";
+  version = "0.6.0";
 
   src = fetchFromGitHub {
     owner = "muesli";
     repo = "duf";
     rev = "v${version}";
-    sha256 = "0n0nvrqrlr75dmf2j6ja615ighzs35cfixn7z9cwdz3vhj1xhc5f";
+    sha256 = "sha256-Wm3gfir6blQFLLi+2bT5Y/5tf7qUxEddJQ7tCYfBGgM=";
   };
 
-  dontStrip = true;
+  vendorSha256 = "0icxy6wbqjqawr6i5skwp1z37fq303p8f95crd8lwn6pjjiqzk4i";
 
-  vendorSha256 = "1jqilfsirj7bkhzywimzf98w2b4s777phb06nsw6lr3bi6nnwzr1";
-
-  buildFlagsArray = [ "-ldflags=" "-X=main.Version=${version}" ];
+  buildFlagsArray = [ "-ldflags=" "-s -w -X=main.Version=${version}" ];
 
   meta = with lib; {
     homepage = "https://github.com/muesli/duf/";
     description = "Disk Usage/Free Utility";
     license = licenses.mit;
     platforms = platforms.unix;
-    maintainers = with maintainers; [ petabyteboy penguwin ];
+    maintainers = with maintainers; [ petabyteboy penguwin SuperSandro2000 ];
   };
 }