diff --git a/tmva/sofie/src/SOFIE_common.cxx b/tmva/sofie/src/SOFIE_common.cxx
index 672d77048ef38..8b07216f63929 100644
--- a/tmva/sofie/src/SOFIE_common.cxx
+++ b/tmva/sofie/src/SOFIE_common.cxx
@@ -54,7 +54,8 @@ std::vector<size_t> ConvertShapeToInt(const std::vector<Dim> & shape){
 std::size_t ConvertShapeToLength(const std::vector<size_t> & shape){
    // Empty shape represent scalar values, so we return a length=1
    std::size_t fLength = 1;
-   for (auto& dim: shape) fLength *= dim;
+   for (const auto &dim : shape)
+   fLength *= dim;
    return fLength;
 }