diff --git a/src/mlpack/methods/ann/layer/elu.hpp b/src/mlpack/methods/ann/layer/elu.hpp
index b87cd2704c..4d93d86c84 100644
--- a/src/mlpack/methods/ann/layer/elu.hpp
+++ b/src/mlpack/methods/ann/layer/elu.hpp
@@ -161,8 +161,8 @@ class ELUType : public Layer<MatType>
    * @param gy The backpropagated error.
    * @param g The calculated gradient.
    */
-  void Backward(const MatType& input,
-                const MatType& output,
+  void Backward(const MatType& /* input */,
+                const MatType& /* output */,
                 const MatType& gy,
                 MatType& g);