diff --git a/src/eval_framework/tasks/base.py b/src/eval_framework/tasks/base.py
index c93f15067..47f402087 100644
--- a/src/eval_framework/tasks/base.py
+++ b/src/eval_framework/tasks/base.py
@@ -190,11 +190,27 @@ def _filter_task_subjects(self, custom_subjects: list[str] | None) -> list[str]
 
         assert hasattr(self, "SUBJECTS") and len(self.SUBJECTS) > 0
         if isinstance(self.SUBJECTS[0], tuple):
-            # subjects are specified as strings but we need tuples
-            filters = [tuple(item.strip() for item in subject.split(",")) for subject in custom_subjects]
+            # subjects are specified as comma-separated strings but tuple positions may each hold a
+            # different type (e.g. tuple[str, int, str]). Infer the expected type per position from an
+            # actual subject and cast each part back to it, so it compares equal to the real values
+            # below instead of just their str() form. "*" is a wildcard sentinel and stays a string.
+            num_items = len(self.SUBJECTS[0])
+            position_types = [type(self.SUBJECTS[0][i]) for i in range(num_items)]
+
+            def cast(raw: str, i: int) -> Any:
+                raw = raw.strip()
+                return raw if raw == "*" else position_types[i](raw)
+
+            filters = []
+            for custom_subject in custom_subjects:
+                parts = custom_subject.split(",")
+                assert len(parts) == num_items, (
+                    f"Subject '{custom_subject}' has {len(parts)} parts, expected {num_items} for "
+                    f"task {self.display_name()}"
+                )
+                filters.append(tuple(cast(part, i) for i, part in enumerate(parts)))
 
             # check if all parts of custom subjects exists (* is a wildcard)
-            num_items = len(self.SUBJECTS[0])
             legal_values = [
                 set([s[i] for s in self.SUBJECTS if isinstance(s, tuple)] + ["*"]) for i in range(num_items)
             ]
@@ -204,18 +220,18 @@ def _filter_task_subjects(self, custom_subjects: list[str] | None) -> list[str]
                     assert v in legal_values[i], f"Subject part {v} not found in task {self.__class__.__name__}"
 
             # filter task subjects. * is a supported wildcard for a specific item in a tuple, e.g. "DE_DE, *"
-            chosen_subjects = []
+            chosen_subjects: list[tuple] = []
             for subject in self.SUBJECTS:
                 subject_tuple = subject if isinstance(subject, tuple) else tuple(str(subject).split(","))
                 for filter in filters:
                     if all(filter[i] == "*" or filter[i] == subject_tuple[i] for i in range(num_items)):
                         chosen_subjects.append(subject_tuple)
                         break
-            return chosen_subjects  # type: ignore[return-value]
+            return chosen_subjects
         else:
             for cs in custom_subjects:
                 assert cs in self.SUBJECTS, f"Subject {cs} not found in task {self.__class__.__name__}"
-            return custom_subjects  # type: ignore[return-value]
+            return custom_subjects
 
     def _load_hf_dataset(self, **kwargs: Any) -> Any:
         cache_dir: str = os.environ.get("HF_DATASET_CACHE_DIR", f"{Path.home()}/.cache/huggingface/datasets")
diff --git a/tests/tests_eval_framework/test_base_task.py b/tests/tests_eval_framework/test_base_task.py
index ad32efa4e..d4b9a7205 100644
--- a/tests/tests_eval_framework/test_base_task.py
+++ b/tests/tests_eval_framework/test_base_task.py
@@ -51,8 +51,23 @@
             ["EN_US,topic1", "DE_DE,topic1"],
             [("EN_US", "topic1"), ("DE_DE", "topic1")],
         ),
+        # mixed-type tuple subjects, tuple[str, int, str]
+        (
+            [("ctx1", 4096, "single"), ("ctx1", 8192, "multi"), ("ctx2", 4096, "single")],
+            ["ctx1,4096,single"],
+            [("ctx1", 4096, "single")],
+        ),
+        (
+            [("ctx1", 4096, "single"), ("ctx1", 8192, "multi"), ("ctx2", 4096, "single")],
+            ["ctx1,*,*"],
+            [("ctx1", 4096, "single"), ("ctx1", 8192, "multi")],
+        ),
         (["subject1", "subject2"], ["invalid_subject"], "AssertionError"),
         ([("EN_US", "topic1"), ("EN_US", "topic2")], ["EN_US,invalid_topic"], "AssertionError"),
+        ([("ctx1", 4096, "single"), ("ctx1", 8192, "multi")], ["ctx1,9999,single"], "AssertionError"),
+        # a part that can't be parsed as its position's type (int here) is a malformed-input error, not
+        # a "valid but disallowed value" error, so it surfaces as ValueError rather than AssertionError.
+        ([("ctx1", 4096, "single"), ("ctx1", 8192, "multi")], ["ctx1,abc,single"], "ValueError"),
     ],
 )
 def test_task_custom_subjects(
@@ -69,8 +84,9 @@ def _get_instruction_text(self, item: dict[str, Any]) -> str:
         def _get_ground_truth(self, item: dict[str, Any]) -> list[str]:
             return []
 
-    if expected_value == "AssertionError":
-        with pytest.raises(AssertionError):
+    expected_exceptions: dict[str, type[Exception]] = {"AssertionError": AssertionError, "ValueError": ValueError}
+    if isinstance(expected_value, str) and expected_value in expected_exceptions:
+        with pytest.raises(expected_exceptions[expected_value]):
             task = MyTask.with_overwrite(num_fewshot=0, custom_subjects=custom_subjects, custom_hf_revision=None)
     else:
         task = MyTask.with_overwrite(num_fewshot=0, custom_subjects=custom_subjects, custom_hf_revision=None)