diff --git a/ext/ReactantCUDAExt.jl b/ext/ReactantCUDAExt.jl
index ea60f2507..6256fa7bb 100644
--- a/ext/ReactantCUDAExt.jl
+++ b/ext/ReactantCUDAExt.jl
@@ -263,6 +263,15 @@ function Adapt.adapt_structure(
     )
 end
 
+function threads_to_workgroupsize(threads, ndrange)
+    total = 1
+    return map(ndrange) do n
+        x = min(div(threads, total), n)
+        total *= x
+        return x
+    end
+end
+
 function (obj::KA.Kernel{ReactantBackend})(args...; ndrange=nothing, workgroupsize=nothing)
     backend = KA.backend(obj)