diff --git a/tensorrt_llm/_torch/custom_ops/trtllm_gen_custom_ops.py b/tensorrt_llm/_torch/custom_ops/trtllm_gen_custom_ops.py
index 53d3ae73a8..ae1b952030 100644
--- a/tensorrt_llm/_torch/custom_ops/trtllm_gen_custom_ops.py
+++ b/tensorrt_llm/_torch/custom_ops/trtllm_gen_custom_ops.py
@@ -6,7 +6,8 @@ import torch
 
 from tensorrt_llm._torch.modules.fused_moe.routing import (
     ROUTING_METHOD_TYPE_TO_CLASS, RoutingMethodType)
-from tensorrt_llm._torch.utils import (Fp4QuantizedTensor, fp4_utils,
+from tensorrt_llm._torch.utils import (ActType_TrtllmGen, Fp4QuantizedTensor,
+                                       fp4_utils,
                                        get_last_power_of_2_num_tokens_buckets,
                                        last_positive_power_of_2,
                                        next_positive_power_of_2)
@@ -393,7 +394,7 @@ def fp4_block_scale_moe_runner(
         routed_scaling_factor: Optional[float],
         routing_method_type: int,
         do_finalize: bool,
-        act_type: int = 0,
+        act_type: int = ActType_TrtllmGen.SwiGlu.value,
         topk_weights: Optional[torch.Tensor] = None,
         topk_ids: Optional[torch.Tensor] = None) -> List[torch.Tensor]:
 
diff --git a/tensorrt_llm/_torch/utils.py b/tensorrt_llm/_torch/utils.py
index e182eee32c..3c243346bb 100644
--- a/tensorrt_llm/_torch/utils.py
+++ b/tensorrt_llm/_torch/utils.py
@@ -49,6 +49,13 @@ class ActivationType(IntEnum):
     Relu2 = 8
 
 
+# Keep this in sync with the ActType enum in
+# cpp/tensorrt_llm/kernels/trtllmGenKernels/batchedGemm/KernelRunner.h
+class ActType_TrtllmGen(IntEnum):
+    SwiGlu = 0
+    Relu2 = 1
+
+
 # IMPORTANT: when adding a new activation type, please update this function.
 # And make sure it aligned with cpp/tensorrt_llm/kernels/cutlass_kernels/include/moe_gemm_kernels.h::isGatedActivation function.
 def is_gated_activation(activation_type: ActivationType) -> bool: