diff --git a/mjx/mujoco/mjx/third_party/warp/jax_experimental/ffi.py b/mjx/mujoco/mjx/third_party/warp/jax_experimental/ffi.py
index 7b10099f..05165b49 100644
--- a/mjx/mujoco/mjx/third_party/warp/jax_experimental/ffi.py
+++ b/mjx/mujoco/mjx/third_party/warp/jax_experimental/ffi.py
@@ -381,6 +381,7 @@ class FfiCallable:
             if arg_name == "return":
                 if arg_type is not None:
                     raise TypeError("Function must not return a value")
+                continue
             else:
                 arg = FfiArg(arg_name, arg_type, arg_name in in_out_argnames)
                 if arg_name in in_out_argnames: