diff --git a/utils/convert-hf-to-gguf-bitnet.py b/utils/convert-hf-to-gguf-bitnet.py
index b11e831b9..52cffda3f 100644
--- a/utils/convert-hf-to-gguf-bitnet.py
+++ b/utils/convert-hf-to-gguf-bitnet.py
@@ -1043,6 +1043,10 @@ def set_vocab(self):
     def set_gguf_parameters(self):
         super().set_gguf_parameters()
 
+        # bitnet-b1.58-2B-4T uses relu^2 in the FFN; the runtime reads it from
+        # <arch>.hidden_activation (see llama_model_bitnet::load_arch_hparams).
+        self.gguf_writer.add_hidden_act("relu2")
+
         self.gguf_writer.add_vocab_size(self.hparams["vocab_size"])
 
         # rope dimension count (required for correct positional encoding)
diff --git a/utils/convert-ms-to-gguf-bitnet.py b/utils/convert-ms-to-gguf-bitnet.py
index edf702788..334839fb5 100644
--- a/utils/convert-ms-to-gguf-bitnet.py
+++ b/utils/convert-ms-to-gguf-bitnet.py
@@ -1157,6 +1157,7 @@ def add_meta_arch(self, params: Params) -> None:
             name = str(params.path_model.parent).split('/')[-1]
 
         self.gguf.add_name                (name)
+        self.gguf.add_hidden_act          ("relu2")
         self.gguf.add_vocab_size          (params.n_vocab)
         self.gguf.add_context_length      (params.n_ctx)
         self.gguf.add_embedding_length    (params.n_embd)