diff --git a/src/jax_finufft/options.py b/src/jax_finufft/options.py
index ec08f77..55c4f60 100644
--- a/src/jax_finufft/options.py
+++ b/src/jax_finufft/options.py
@@ -40,6 +40,9 @@ class GpuMethod(IntEnum):
 
 @dataclass(frozen=True)
 class Opts:
+
+    # These correspond to the default cufinufft options
+    # set in vendor/finufft/src/cuda/cufinufft.cu
     modeord: bool = False
     chkbnds: bool = True
     debug: DebugLevel = DebugLevel.Silent
@@ -59,12 +62,12 @@ class Opts:
     gpu_upsampfac: float = 2.0
     gpu_method: GpuMethod = 0
     gpu_sort: bool = True
-    gpu_binsizex: int = -1
-    gpu_binsizey: int = -1
-    gpu_binsizez: int = -1
-    gpu_obinsizex: int = -1
-    gpu_obinsizey: int = -1
-    gpu_obinsizez: int = -1
+    gpu_binsizex: int = 0
+    gpu_binsizey: int = 0
+    gpu_binsizez: int = 0
+    gpu_obinsizex: int = 0
+    gpu_obinsizey: int = 0
+    gpu_obinsizez: int = 0
     gpu_maxsubprobsize: int = 1024
     gpu_kerevalmeth: bool = True
     gpu_spreadinterponly: bool = False