diff --git a/src/cc2olx/validators/cli.py b/src/cc2olx/validators/cli.py
index ee8482f..bfa1e23 100644
--- a/src/cc2olx/validators/cli.py
+++ b/src/cc2olx/validators/cli.py
@@ -19,9 +19,7 @@ class LinkSourceValidator:
     IPV6_REGEX = r"\[[0-9a-f:.]+\]"  # (simple regex, validated later)
 
     # Host patterns
-    HOSTNAME_REGEX = (
-        rf"[a-z{UL}0-9](?:[a-z{UL}0-9-]{{0,61}}[a-z{UL}0-9])?"
-    )
+    HOSTNAME_REGEX = rf"[a-z{UL}0-9](?:[a-z{UL}0-9-]{{0,61}}[a-z{UL}0-9])?"
     # Max length for domain name labels is 63 characters per RFC 1034 sec. 3.1
     DOMAIN_REGEX = rf"(?:\.(?!-)[a-z{UL}0-9-]{{1,63}}(?<!-))*"
     TLD_REGEX = (
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 5cf6a2a..5c81cd2 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -86,7 +86,7 @@ def test_parse_args_with_incorrect_relative_links_source(imscc_file: Path) -> No
     """
     Test arguments parser detects incorrect relative links sources.
     """
-    relative_links_source = "ws://example.com",
+    relative_links_source = "ws://example.com"
 
     with pytest.raises(SystemExit):
         parse_args(["-i", str(imscc_file), "-s", relative_links_source])
diff --git a/tests/test_validators/test_cli.py b/tests/test_validators/test_cli.py
index b75a0f5..5d11159 100644
--- a/tests/test_validators/test_cli.py
+++ b/tests/test_validators/test_cli.py
@@ -19,7 +19,7 @@ class TestLinkSourceValidator:
             "http://192.168.0.1",
             "http://192.168.0.1:8000/",
             "https://[2001:0db8:85a3::8a2e:0370:7334]/",
-        )
+        ),
     )
     def test_original_value_is_returned_if_it_is_valid(self, links_source: str) -> None:
         """
@@ -39,7 +39,7 @@ def test_original_value_is_returned_if_it_is_valid(self, links_source: str) -> N
             "https://m192.168.0.1",
             "https://2001:0db8:85a3::8a2e:0370:7334/",
             "https://[2001:db8:85a3::8a2e:0370:7334::]/",
-        )
+        ),
     )
     def test_wrong_values_are_detected(self, links_source) -> None:
         """