diff --git a/tensorrt_llm/_torch/custom_ops/cute_dsl_custom_ops.py b/tensorrt_llm/_torch/custom_ops/cute_dsl_custom_ops.py
index f01da1dc55ed..da8b2175bdcf 100644
--- a/tensorrt_llm/_torch/custom_ops/cute_dsl_custom_ops.py
+++ b/tensorrt_llm/_torch/custom_ops/cute_dsl_custom_ops.py
@@ -44,7 +44,6 @@
 SWIGLU_LIMIT_SCALAR_DISABLED = -1.0
 _CUTEDSL_FC2_N_TILE_SIZE_ENV = "TRTLLM_CUTEDSL_FC2_N_TILE_SIZE"
 _CUTEDSL_FC2_N_TILE_SIZES = (128, 256)
-_CUTEDSL_FC2_DEFAULT_N_TILE_SIZE = 128
 
 # Legacy Rubin ops use a float sentinel for absent SiTU soft-caps.
 # The Blackwell act-fusion op accepts Optional[float] directly.
@@ -192,10 +191,12 @@ def _get_sm107_nvfp4_default_mma_config(
 
 @functools.lru_cache(maxsize=1)
 def _get_cutedsl_fc2_n_tile_size_override() -> Optional[int]:
-    value = os.environ.get(
-        _CUTEDSL_FC2_N_TILE_SIZE_ENV,
-        str(_CUTEDSL_FC2_DEFAULT_N_TILE_SIZE),
-    )
+    """Return the FC2 N tile pinned by the user, or None to autotune over all of them.
+
+    Unset and ``0`` both autotune. ``128`` or ``256`` pins that tile for shapes
+    where it is known to win end to end.
+    """
+    value = os.environ.get(_CUTEDSL_FC2_N_TILE_SIZE_ENV, "0")
     if value == "0":
         return None
     valid_values = tuple(
diff --git a/tests/unittest/_torch/moe/fused_moe/test_cutedsl_fc2_tuning.py b/tests/unittest/_torch/moe/fused_moe/test_cutedsl_fc2_tuning.py
index 0c7e4cf01a54..bddf78405490 100644
--- a/tests/unittest/_torch/moe/fused_moe/test_cutedsl_fc2_tuning.py
+++ b/tests/unittest/_torch/moe/fused_moe/test_cutedsl_fc2_tuning.py
@@ -61,6 +61,7 @@ def _make_runner(
             [
                 ((128, 128), (1, 1), False),
                 ((128, 128), (1, 2), False),
+                ((128, 256), (1, 1), False),
             ],
         ),
         (
@@ -97,7 +98,7 @@ def test_fc2_n_tile_size_override(
     tactics = runner.get_valid_tactics(inputs, OptimizationProfile())
 
     assert tactics == expected_tactics
-    expected_override = 128 if env_value is None else (None if env_value == "0" else int(env_value))
+    expected_override = None if env_value in (None, "0") else int(env_value)
     assert runner._get_default_tactic()[0][1] == (expected_override or 128)
     if expected_override is None:
         assert "fc2_n_tile_size_override" not in runner.unique_id()