diff --git a/opensora/schedulers/rf/rectified_flow.py b/opensora/schedulers/rf/rectified_flow.py
index 58d7b48..8acaff5 100644
--- a/opensora/schedulers/rf/rectified_flow.py
+++ b/opensora/schedulers/rf/rectified_flow.py
@@ -15,6 +15,11 @@ def timestep_transform(
     scale=1.0,
     num_timesteps=1,
 ):
+    # Force fp16 input to fp32 to avoid nan output
+    for key in ["height", "width", "num_frames"]:
+        if model_kwargs[key].dtype == torch.float16:
+            model_kwargs[key] = model_kwargs[key].float()
+            
     t = t / num_timesteps
     resolution = model_kwargs["height"] * model_kwargs["width"]
     ratio_space = (resolution / base_resolution).sqrt()