diff --git a/mamba_ssm/modules/mamba2.py b/mamba_ssm/modules/mamba2.py
index 36b16d471..cdc047fb0 100644
--- a/mamba_ssm/modules/mamba2.py
+++ b/mamba_ssm/modules/mamba2.py
@@ -142,7 +142,7 @@ def __init__(
         if self.rmsnorm:
             assert RMSNormGated is not None
             self.norm = RMSNormGated(self.d_ssm, eps=1e-5, norm_before_gate=self.norm_before_gate,
-                                     group_size=self.d_ssm // ngroups, **factory_kwargs)
+                                     group_size=self.d_ssm // self.ngroups, **factory_kwargs)
 
         if self.process_group is None:
             self.out_proj = nn.Linear(self.d_inner, self.d_model, bias=bias, **factory_kwargs)