diff --git a/python/cudnn/frost/device.py b/python/cudnn/frost/device.py
index c66f60177..de5db84ef 100644
--- a/python/cudnn/frost/device.py
+++ b/python/cudnn/frost/device.py
@@ -119,20 +119,22 @@ def shared_memory_per_block_optin(device: int) -> int:
     return int(_ck(*drv.cuDeviceGetAttribute(drv.CUdevice_attribute.CU_DEVICE_ATTRIBUTE_MAX_SHARED_MEMORY_PER_BLOCK_OPTIN, handle)))
 
 
-# CU_DEVICE_ATTRIBUTE_MAX_OVERSIZED_SHARED_MEMORY_PER_BLOCK. Named in CUDA 13.4's
-# cuda.h; cuda-python's CUdevice_attribute does not carry it yet, so ask by ordinal.
-_ATTR_MAX_OVERSIZED_SHARED_MEMORY_PER_BLOCK = 150
-
-
 @functools.lru_cache(maxsize=None)
 def oversized_shared_memory_per_block(device: int) -> int:
     """Per-CTA SMEM ceiling in the *oversized* carveout (327 KiB vs the 227 KiB
     opt-in limit on SM 10.7), which the part gives by shrinking L1 to 8 kB — free for
     a TMA-fed GEMM. 0 when the driver has no such mode."""
     drv = _driver()
+    # CU_DEVICE_ATTRIBUTE_MAX_OVERSIZED_SHARED_MEMORY_PER_BLOCK arrived in CUDA 13.4.
+    # A driver older than that has no such mode -> 0 by design (not an error), and we
+    # do not touch the enum member (which an older cuda-python's CUdevice_attribute
+    # does not carry -- passing a bare ordinal would raise, since the binding reads
+    # attrib.value). From 13.4 the attribute is real: query it and let a genuine
+    # failure raise rather than masking it as 0.
+    if int(_ck(*drv.cuDriverGetVersion())) < 13040:
+        return 0
     handle = _device_handle(device)
-    err, value = drv.cuDeviceGetAttribute(_ATTR_MAX_OVERSIZED_SHARED_MEMORY_PER_BLOCK, handle)
-    return int(value) if int(err) == 0 else 0
+    return int(_ck(*drv.cuDeviceGetAttribute(drv.CUdevice_attribute.CU_DEVICE_ATTRIBUTE_MAX_OVERSIZED_SHARED_MEMORY_PER_BLOCK, handle)))
 
 
 @functools.lru_cache(maxsize=None)