diff --git a/pinecone/utils/filter_builder.py b/pinecone/utils/filter_builder.py
index 28e2d80b..2f7f8c74 100644
--- a/pinecone/utils/filter_builder.py
+++ b/pinecone/utils/filter_builder.py
@@ -117,12 +117,20 @@ def __ne__(self, value: object) -> Condition:  # type: ignore[override]
 
     # -- set operators --------------------------------------------------------
 
+    def _require_list(self, op: str, values: Any) -> None:
+        if not isinstance(values, (list, tuple)):
+            raise TypeError(
+                f"{op} requires a list of values, got {type(values).__name__}"
+            )
+
     def is_in(self, values: list[str | int | float | bool]) -> Condition:
         """``$in`` — value is in the given list."""
+        self._require_list("is_in", values)
         return Condition({self._name: {"$in": values}})
 
     def not_in(self, values: list[str | int | float | bool]) -> Condition:
         """``$nin`` — value is not in the given list."""
+        self._require_list("not_in", values)
         return Condition({self._name: {"$nin": values}})
 
     # -- exists operator ------------------------------------------------------
diff --git a/tests/unit/utils/test_filter_builder.py b/tests/unit/utils/test_filter_builder.py
index 4b31ffff..cd25649b 100644
--- a/tests/unit/utils/test_filter_builder.py
+++ b/tests/unit/utils/test_filter_builder.py
@@ -64,6 +64,18 @@ def test_field_not_in(self) -> None:
         result = Field("tag").not_in(["spam"]).to_dict()
         assert result == {"tag": {"$nin": ["spam"]}}
 
+    def test_field_is_in_accepts_tuple(self) -> None:
+        result = Field("color").is_in(("red", "blue")).to_dict()
+        assert result == {"color": {"$in": ("red", "blue")}}
+
+    def test_is_in_requires_list(self) -> None:
+        with pytest.raises(TypeError, match="list"):
+            Field("genre").is_in("drama")  # type: ignore[arg-type]
+
+    def test_not_in_requires_list(self) -> None:
+        with pytest.raises(TypeError, match="list"):
+            Field("genre").not_in("drama")  # type: ignore[arg-type]
+
 
 class TestFieldExists:
     def test_field_exists(self) -> None: