diff --git a/src/mlpack/methods/ann/layer/softmin.hpp b/src/mlpack/methods/ann/layer/softmin.hpp
index 220e27fbe1..e7146e585e 100644
--- a/src/mlpack/methods/ann/layer/softmin.hpp
+++ b/src/mlpack/methods/ann/layer/softmin.hpp
@@ -68,7 +68,7 @@ class SoftminType : public Layer<MatType>
    * @param gy The backpropagated error.
    * @param g The calculated gradient.
    */
-  void Backward(const MatType& input,
+  void Backward(const MatType& /* input */,
                 const MatType& output,
                 const MatType& gy,
                 MatType& g);