diff --git a/src/mlpack/core/data/load_impl.hpp b/src/mlpack/core/data/load_impl.hpp
index e3b38602ba..8f298379fb 100644
--- a/src/mlpack/core/data/load_impl.hpp
+++ b/src/mlpack/core/data/load_impl.hpp
@@ -31,6 +31,8 @@ namespace data {
 
 namespace details{
 
+namespace{
+
 template<typename Tokenizer>
 std::vector<std::string> ToTokens(Tokenizer &lineTok)
 {
@@ -97,6 +99,8 @@ void MapToNumerical(const std::vector<std::string> &tokens,
 
 }
 
+}
+
 template<typename eT>
 bool inline inplace_transpose(arma::Mat<eT>& X)
 {