diff --git a/Framework/Algorithms/src/CalculatePlaczekSelfScattering.cpp b/Framework/Algorithms/src/CalculatePlaczekSelfScattering.cpp
index bf376d0db229b3ba360f1de5d91661bfd720924d..c13fbe283c6d4ac5d42334c413d04b9fab4b684c 100644
--- a/Framework/Algorithms/src/CalculatePlaczekSelfScattering.cpp
+++ b/Framework/Algorithms/src/CalculatePlaczekSelfScattering.cpp
@@ -37,7 +37,7 @@ getSampleSpeciesInfo(const API::MatrixWorkspace_const_sptr ws) {
     atomSpecies[element.atom->symbol] = atomMap;
     totalStoich += element.multiplicity;
   }
-  for (auto atom : atomSpecies) {
+  for (const auto atom : atomSpecies) {
     atom.second["concentration"] = atom.second["stoich"] / totalStoich;
   }
   return atomSpecies;