diff --git a/pkgs/development/python-modules/cmarkgfm/default.nix b/pkgs/development/python-modules/cmarkgfm/default.nix
index 5b94dc78cd6..7379d6dc6c9 100644
--- a/pkgs/development/python-modules/cmarkgfm/default.nix
+++ b/pkgs/development/python-modules/cmarkgfm/default.nix
@@ -1,25 +1,29 @@
-{ lib, buildPythonPackage, fetchPypi, cffi, pytest }:
+{ lib
+, buildPythonPackage
+, cffi
+, fetchPypi
+, pytestCheckHook
+}:
 
 buildPythonPackage rec {
   pname = "cmarkgfm";
-  version = "0.5.2";
+  version = "0.5.3";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "e7d65b90645faa55c28886d01f658235af08b4c4edbf9d959518a17007dd20b4";
+    sha256 = "sha256-tqVJq6Mnq9mG1nSM8hyGN9dBx2hQ5/773vjSi/4TjjI=";
   };
 
   propagatedBuildInputs = [ cffi ];
 
-  checkInputs = [ pytest ];
+  checkInputs = [ pytestCheckHook ];
 
-  checkPhase = ''
-    py.test
-  '';
+  pythonImportsCheck = [ "cmarkgfm" ];
 
   meta = with lib; {
     description = "Minimal bindings to GitHub's fork of cmark";
     homepage = "https://github.com/jonparrott/cmarkgfm";
     license = licenses.mit;
+    maintainers = with maintainers; [ fab ];
   };
 }
diff --git a/pkgs/development/python-modules/libagent/default.nix b/pkgs/development/python-modules/libagent/default.nix
index 47be977755c..5334513e23c 100644
--- a/pkgs/development/python-modules/libagent/default.nix
+++ b/pkgs/development/python-modules/libagent/default.nix
@@ -25,7 +25,7 @@ buildPythonPackage rec {
   meta = with lib; {
     description = "Using hardware wallets as SSH/GPG agent";
     homepage = "https://github.com/romanz/trezor-agent";
-    license = licenses.gpl3;
+    license = licenses.lgpl3Only;
     maintainers = with maintainers; [ np ];
   };
 }
diff --git a/pkgs/development/python-modules/ndjson/default.nix b/pkgs/development/python-modules/ndjson/default.nix
index 715a1989b45..b69e8401eb5 100644
--- a/pkgs/development/python-modules/ndjson/default.nix
+++ b/pkgs/development/python-modules/ndjson/default.nix
@@ -16,6 +16,7 @@ buildPythonPackage rec {
     homepage = "https://github.com/rhgrant10/ndjson";
     description = "JsonDecoder";
     platforms = platforms.unix;
+    license = licenses.gpl3Only;
     maintainers = with maintainers; [ freezeboy ];
   };
 }
diff --git a/pkgs/development/python-modules/pkutils/default.nix b/pkgs/development/python-modules/pkutils/default.nix
index d674e876b14..c383f5ff86c 100644
--- a/pkgs/development/python-modules/pkutils/default.nix
+++ b/pkgs/development/python-modules/pkutils/default.nix
@@ -1,5 +1,4 @@
 { lib
-, pythonOlder
 , buildPythonPackage
 , isPy3k
 , fetchFromGitHub
diff --git a/pkgs/development/python-modules/salmon-mail/default.nix b/pkgs/development/python-modules/salmon-mail/default.nix
index 0b8edf8bdd9..52aa8a98e1e 100644
--- a/pkgs/development/python-modules/salmon-mail/default.nix
+++ b/pkgs/development/python-modules/salmon-mail/default.nix
@@ -28,7 +28,7 @@ buildPythonPackage rec {
   meta = with lib; {
     homepage = "https://salmon-mail.readthedocs.org/";
     description = "Pythonic mail application server";
-    license = licenses.gpl3;
+    license = licenses.gpl3Only;
     maintainers = with maintainers; [ jluttine ];
   };
 }
diff --git a/pkgs/development/python-modules/semver/default.nix b/pkgs/development/python-modules/semver/default.nix
index c281a6d6b0d..cb4578671b9 100644
--- a/pkgs/development/python-modules/semver/default.nix
+++ b/pkgs/development/python-modules/semver/default.nix
@@ -1,27 +1,34 @@
 { lib
-, fetchFromGitHub
 , buildPythonPackage
+, fetchFromGitHub
+, pytest-cov
 , pytestCheckHook
-, pytestcov
 }:
 
 buildPythonPackage rec {
   pname = "semver";
-  version = "2.10.2";
+  version = "2.13.0";
 
   src = fetchFromGitHub {
     owner = "python-semver";
     repo = "python-semver";
     rev = version;
-    sha256 = "0yxjmcgk5iwp53l9z1cg0ajrj18i09ircs11ifpdrggzm8n1blf3";
+    sha256 = "sha256-IWTo/P9JRxBQlhtcH3JMJZZrwAA8EALF4dtHajWUc4w=";
   };
 
-  preCheck = "rm -rf dist"; # confuses source vs dist imports in pytest
-  checkInputs = [ pytestCheckHook pytestcov ];
+  checkInputs = [
+    pytest-cov
+    pytestCheckHook
+  ];
+
+  # Confuses source vs dist imports in pytest
+  preCheck = "rm -r dist";
+
+  pythonImportsCheck = [ "semver" ];
 
   meta = with lib; {
     description = "Python package to work with Semantic Versioning (http://semver.org/)";
-    homepage = "https://python-semver.readthedocs.io/en/latest/";
+    homepage = "https://python-semver.readthedocs.io/";
     license = licenses.bsd3;
     maintainers = with maintainers; [ np ];
   };