diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py b/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
index 96af43fdb..b6d409eb2 100644
--- a/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
@@ -1424,8 +1424,8 @@ class NonlinAttentionModule(nn.Module):
         )
         # give it a high limit, because it is quite high-dimensional and is
         # a projection of a lower-dimensional embedding.
-        self.whiten = Whiten(num_groups=1,
-                             whitening_limit=40.0,
+        self.whiten = Whiten(num_groups=2,
+                             whitening_limit=20.0,
                              prob=(0.025, 0.25),
                              grad_scale=0.01)