diff --git a/vllm/model_executor/layers/quantization/mxfp4.py b/vllm/model_executor/layers/quantization/mxfp4.py
index 0ad1b8931270..8856eb1e2e49 100644
--- a/vllm/model_executor/layers/quantization/mxfp4.py
+++ b/vllm/model_executor/layers/quantization/mxfp4.py
@@ -1258,7 +1258,7 @@ def apply_monolithic(
             topk_weights=routing_weights,
             topk_ids=selected_experts,
             n_experts_per_token=layer.top_k,
-            activation=layer.activation,
+            activation=layer.activation.value,
             num_experts=layer.local_num_experts,
             is_mxfp4=True,
         )