diff --git a/tinygrad/runtime/ops_cuda.py b/tinygrad/runtime/ops_cuda.py
index ef01369133..4e83f869bd 100644
--- a/tinygrad/runtime/ops_cuda.py
+++ b/tinygrad/runtime/ops_cuda.py
@@ -87,7 +87,7 @@ class CUDAAllocator(LRUAllocator):
     check(cuda.cuEventRecord(sync_event, None))
     check(cuda.cuCtxSetCurrent(dest_dev.context))
     check(cuda.cuStreamWaitEvent(None, sync_event, 0)) # sync the default stream on the dest dev
-  def offset(self, buf, size:int, offset:int): return ctypes.c_ulong(buf.value + offset)
+  def offset(self, buf, size:int, offset:int): return cuda.CUdeviceptr_v2(buf.value + offset)
 
 class CUDADevice(Compiled):
   devices: List[CUDADevice] = []