diff --git a/src/mlpack/methods/ann/layer/isrlu_impl.hpp b/src/mlpack/methods/ann/layer/isrlu_impl.hpp
index b69ffbf8bb..8ee468849f 100644
--- a/src/mlpack/methods/ann/layer/isrlu_impl.hpp
+++ b/src/mlpack/methods/ann/layer/isrlu_impl.hpp
@@ -33,7 +33,7 @@ void ISRLU<InputDataType, OutputDataType>::Forward(
   for (size_t i = 0; i < input.n_elem; ++i)
   {
     output(i) = (input(i) >= 0) ? input(i) : input(i) %
-                (1 / std::sqrt(1 + alpha * (input(i) % input(i))));
+                (1 / arma::sqrt(1 + alpha * (input(i) % input(i))));
   }
 
   if (!deterministic)
@@ -42,7 +42,7 @@ void ISRLU<InputDataType, OutputDataType>::Forward(
     for (size_t i = 0; i < input.n_elem; ++i)
     {
       derivative(i) = (input(i) >= 0) ? 1 :
-          std::pow(output(i), 3) / std::pow(input(i), 3);
+          arma::pow(output(i), 3) / arma::pow(input(i), 3);
     }
   }
 }