diff --git a/tests/debug_wo_a3.py b/tests/debug_wo_a3.py
index b276179c..8245f422 100644
--- a/tests/debug_wo_a3.py
+++ b/tests/debug_wo_a3.py
@@ -45,7 +45,7 @@ runner._ensure_initialized()
 
 # Compute activation gs
 with torch.no_grad():
-    _, _, gs = quantize_to_nvfp4(o_g.reshape(T, GI)[:1])
+    _, _, gs = quantize_to_nvfp4(o_g[:, 0, :])  # use first group's activation
 print(f"\nActivation gs from sample: {gs:.6f}")
 print(f"Runner gs: {runner._activation_global_scale:.6f}")