diff --git a/src/coreComponents/mesh/mpiCommunications/CommID.hpp b/src/coreComponents/mesh/mpiCommunications/CommID.hpp
index 143e55eb18c..7c904234f07 100644
--- a/src/coreComponents/mesh/mpiCommunications/CommID.hpp
+++ b/src/coreComponents/mesh/mpiCommunications/CommID.hpp
@@ -59,7 +59,7 @@ class CommID
   CommID & operator=( CommID && ) = delete;
 
   /// user defined conversion operator to int
-  constexpr operator int()
+  constexpr operator int() const
   { return m_id; }
 
 private: