--- lib64/python3/dist-packages/vllm/model_executor/models/llama.py
+++ lib64/python3/dist-packages/vllm/model_executor/models/llama.py
@@ -128,8 +128,8 @@
             assert tp_size % self.total_num_kv_heads == 0
         self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)
         # MistralConfig has an optional head_dim introduced by Mistral-Nemo
-        self.head_dim = getattr(config, "head_dim",
-                                self.hidden_size // self.total_num_heads)
+        def_head_dim = self.hidden_size // self.total_num_heads
+        self.head_dim = getattr(config, "head_dim", def_head_dim) or def_head_dim
         # Phi models introduced a partial_rotary_factor parameter in the config
         partial_rotary_factor = getattr(config, "partial_rotary_factor", 1)
         self.rotary_dim = int(partial_rotary_factor * self.head_dim)