diff --git a/.github/workflows/run-tests-workflow.yml b/.github/workflows/run-tests-workflow.yml
index ab0c818e1..9ef38457a 100644
--- a/.github/workflows/run-tests-workflow.yml
+++ b/.github/workflows/run-tests-workflow.yml
@@ -25,6 +25,14 @@ jobs:
             python-version: 3.7
             test-env: "PyQt5~=5.12.0"
 
+          - os: ubuntu-20.04
+            python-version: 3.6
+            test-env: "PyQt5~=5.15.0"
+
+          - os: ubuntu-20.04
+            python-version: 3.7
+            test-env: "PyQt5~=5.15.0"
+
           - os: ubuntu-20.04
             python-version: 3.8
             test-env: "PyQt5~=5.14.0"
diff --git a/orangecanvas/application/application.py b/orangecanvas/application/application.py
index e03b0d7cd..25254ee10 100644
--- a/orangecanvas/application/application.py
+++ b/orangecanvas/application/application.py
@@ -183,9 +183,13 @@ def argumentParser():
                 os.environ.get("QT_SCALE_FACTOR_ROUNDING_POLICY"),
                 Qt.HighDpiScaleFactorRoundingPolicy.PassThrough
             )
+
+            def converter(value):
+                # dict.get wrapper due to https://bugs.python.org/issue16516
+                return HighDpiScaleFactorRoundingPolicyLookup.get(value)
             parser.add_argument(
                 "-scale-factor-rounding-policy",
-                type=HighDpiScaleFactorRoundingPolicyLookup.get,
+                type=converter,
                 choices=[*HighDpiScaleFactorRoundingPolicyLookup.values(), None],
                 default=default,
             )
diff --git a/orangecanvas/application/tests/test_application.py b/orangecanvas/application/tests/test_application.py
index 922429470..479324a3e 100644
--- a/orangecanvas/application/tests/test_application.py
+++ b/orangecanvas/application/tests/test_application.py
@@ -23,6 +23,12 @@ def test_application(self):
         ])
         self.assertEqual(res.returncode, 0)
 
+    def test_application_help(self):
+        res = sh.python_run([
+            "-m", "orangecanvas", "--help"
+        ])
+        self.assertEqual(res.returncode, 0)
+
 
 def remove_after_exit(fname):
     appmod.run_after_exit([