diff --git a/tests/test_pipeline_real_weights.py b/tests/test_pipeline_real_weights.py
index 3ee66e87..71c2f76f 100644
--- a/tests/test_pipeline_real_weights.py
+++ b/tests/test_pipeline_real_weights.py
@@ -172,6 +172,7 @@ def main():
         intermediate_size=INTERMEDIATE_SIZE, max_num_tokens=NUM_TOKENS,
         top_k=TOP_K, device=DEVICE,
     )
+    runner._ensure_stacked()
     # Just use the runner's scale assembly
     l1_gsa = torch.full((NUM_EXPERTS,), l1_gs, dtype=torch.float32, device=DEVICE)
     l1_scale_a = runner._assemble_scales_cudagraph_safe(