diff --git a/compliance_checker/cf/cf_1_6.py b/compliance_checker/cf/cf_1_6.py
index f4ff4710..f059e0f7 100644
--- a/compliance_checker/cf/cf_1_6.py
+++ b/compliance_checker/cf/cf_1_6.py
@@ -443,8 +443,7 @@ def check_valid_range_and_valid_min_max_present(self, ds):
         total = 0
 
         for variable in ds.variables.values():
-            if (hasattr(variable, "valid_max") or
-                hasattr(variable, "valid_min")):
+            if hasattr(variable, "valid_max") or hasattr(variable, "valid_min"):
                 total += 1
                 # if there's also valid_range in addition to
                 # valid_min/valid_max, this is not compliant
diff --git a/compliance_checker/tests/test_cf.py b/compliance_checker/tests/test_cf.py
index 292bfd82..c86c115c 100644
--- a/compliance_checker/tests/test_cf.py
+++ b/compliance_checker/tests/test_cf.py
@@ -1300,7 +1300,9 @@ def test_check_time_coordinate(self):
         # NB: >= 60 seconds is nonstandard, but isn't actually a CF requirement
         # until CF 1.9 onwards
         dataset.variables["time"].units = "months since 0-1-1 23:00:60"
-        dataset.variables["time"].climatology = (
+        dataset.variables[
+            "time"
+        ].climatology = (
             "nonexistent_variable_reference_only_used_to_test_year_zero_failure"
         )
         results = self.cf.check_time_coordinate(dataset)
@@ -2951,9 +2953,9 @@ def test_bad_lsid(self):
             messages = results[0].msgs
             assert results[0].value[0] < results[0].value[1]
             assert len(messages) == 1
-            taxon_lsid[0] = (
-                "http://www.lsid.info/urn:lsid:marinespecies.org:taxname:99999999999"
-            )
+            taxon_lsid[
+                0
+            ] = "http://www.lsid.info/urn:lsid:marinespecies.org:taxname:99999999999"
             results = self.cf.check_taxa(dataset)
             assert messages[0].startswith(
                 "Taxon id must match one of the following forms:",