diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 247eea3..ae00040 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -14,7 +14,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v1
         with:
-          python-version: 3.8
+          python-version: 3.9
 
       - name: Install Python dependencies
         run: python -m pip install black flake8
@@ -25,6 +25,6 @@ jobs:
           github_token: ${{ secrets.github_token }}
           # Enable linters
           black: true
-          black_args: "-l 99"
+          black_args: "-l 99 --diff --color"
           flake8: true
           flake8_args: "--max-line-length=99 --extend-ignore=E203,E501"
diff --git a/osaca/db_interface.py b/osaca/db_interface.py
index 09c352d..800289c 100755
--- a/osaca/db_interface.py
+++ b/osaca/db_interface.py
@@ -615,7 +615,7 @@ def _get_full_instruction_name(instruction_form):
 
 def __represent_none(self, data):
     """Get YAML None representation."""
-    return self.represent_scalar(u"tag:yaml.org,2002:null", u"~")
+    return self.represent_scalar("tag:yaml.org,2002:null", "~")
 
 
 def _create_yaml_object():
diff --git a/osaca/parser/parser_AArch64.py b/osaca/parser/parser_AArch64.py
index 3e80f83..4cf8c78 100755
--- a/osaca/parser/parser_AArch64.py
+++ b/osaca/parser/parser_AArch64.py
@@ -540,7 +540,7 @@ class ParserAArch64(BaseParser):
         exponent = int(ieee_val["exponent"], 10)
         if ieee_val["e_sign"] == "-":
             exponent *= -1
-        return float(ieee_val["mantissa"]) * (10 ** exponent)
+        return float(ieee_val["mantissa"]) * (10**exponent)
 
     def parse_register(self, register_string):
         raise NotImplementedError
diff --git a/osaca/semantics/hw_model.py b/osaca/semantics/hw_model.py
index fc80a84..ef34761 100755
--- a/osaca/semantics/hw_model.py
+++ b/osaca/semantics/hw_model.py
@@ -811,4 +811,4 @@ class MachineModel(object):
 
     def __represent_none(self, yaml_obj, data):
         """YAML representation for `None`"""
-        return yaml_obj.represent_scalar(u"tag:yaml.org,2002:null", u"~")
+        return yaml_obj.represent_scalar("tag:yaml.org,2002:null", "~")