diff --git a/src/mcore_bridge/model/modules/gated_delta_net.py b/src/mcore_bridge/model/modules/gated_delta_net.py
index d2ee0dd..84dd0fd 100644
--- a/src/mcore_bridge/model/modules/gated_delta_net.py
+++ b/src/mcore_bridge/model/modules/gated_delta_net.py
@@ -184,7 +184,13 @@ def forward(
             # TODO: support inference
             raise NotImplementedError('GDN does not support inference for now.')
 
-        cu_seqlens = None if packed_seq_params is None else packed_seq_params.cu_seqlens_q
+        # Only use packed sequences when qkv_format is 'thd' and cu_seqlens_q is present
+        cu_seqlens = None
+        if (packed_seq_params is not None and 
+            hasattr(packed_seq_params, 'qkv_format') and 
+            packed_seq_params.qkv_format == 'thd' and
+            packed_seq_params.cu_seqlens_q is not None):
+            cu_seqlens = packed_seq_params.cu_seqlens_q
         # Input projection
         num_key_heads_per_device = self.num_key_heads // self.tp_size // cp_size
         nvtx_range_push(suffix='in_proj')