diff --git a/openml/datasets/dataset.py b/openml/datasets/dataset.py
index d9eee278d..77f2fedd0 100644
--- a/openml/datasets/dataset.py
+++ b/openml/datasets/dataset.py
@@ -364,8 +364,10 @@ def __eq__(self, other: Any) -> bool:
 
         # check that common keys and values are identical
         ignore_fields = server_fields | cache_fields
-        self_keys = set(self.__dict__.keys()) - ignore_fields
-        other_keys = set(other.__dict__.keys()) - ignore_fields
+
+        self_keys = set(self.__dict__) - ignore_fields
+        other_keys = set(other.__dict__) - ignore_fields
+
         return self_keys == other_keys and all(
             self.__dict__[key] == other.__dict__[key] for key in self_keys
         )
@@ -616,7 +618,7 @@ def _parse_data_from_pq(self, data_file: Path) -> tuple[list[str], list[bool], p
             data = pd.read_parquet(data_file)
         except Exception as e:
             raise Exception(f"File: {data_file}") from e
-        categorical = [data[c].dtype.name == "category" for c in data.columns]
+        categorical = [isinstance(data[c].dtype, pd.CategoricalDtype) for c in data.columns]
         attribute_names = list(data.columns)
         return attribute_names, categorical, data
 
diff --git a/openml/flows/functions.py b/openml/flows/functions.py
index 0a2058890..e7ddcdd69 100644
--- a/openml/flows/functions.py
+++ b/openml/flows/functions.py
@@ -510,7 +510,7 @@ def assert_flows_equal(  # noqa: C901, PLR0912, PLR0913, PLR0915
     ]
     ignored_by_python_api = ["binary_url", "binary_format", "binary_md5", "model", "_entity_id"]
 
-    for key in set(flow1.__dict__.keys()).union(flow2.__dict__.keys()):
+    for key in set(flow1.__dict__).union(flow2.__dict__):
         if key in generated_by_the_server + ignored_by_python_api:
             continue
         attr1 = getattr(flow1, key, None)
@@ -519,7 +519,7 @@ def assert_flows_equal(  # noqa: C901, PLR0912, PLR0913, PLR0915
             if not (isinstance(attr1, dict) and isinstance(attr2, dict)):
                 raise TypeError("Cannot compare components because they are not dictionary.")
 
-            for name in set(attr1.keys()).union(attr2.keys()):
+            for name in set(attr1).union(attr2):
                 if name not in attr1:
                     raise ValueError(
                         f"Component {name} only available in argument2, but not in argument1.",