diff --git a/include/musica/util.hpp b/include/musica/util.hpp
index 483957e5..0d20fcd3 100644
--- a/include/musica/util.hpp
+++ b/include/musica/util.hpp
@@ -122,7 +122,7 @@ namespace musica
     /// @param target The target array of name-index Mappings
     /// @param error The Error to populate if a Mapping is not found
     /// @return The array of IndexMappings
-    IndexMappings CreateIndexMappings(Configuration configuration, const Mappings source, const Mappings target, Error* error);
+    IndexMappings CreateIndexMappings(const Configuration configuration, const Mappings source, const Mappings target, Error* error);
 
     /// @brief Copies data from one array to another using IndexMappings
     /// @param mappings The array of IndexMappings
diff --git a/src/util.cpp b/src/util.cpp
index 163ef585..453580f5 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -178,7 +178,7 @@ namespace musica
     delete[] mappings->mappings_;
   }
 
-  IndexMappings CreateIndexMappings(Configuration configuration, const Mappings source, const Mappings target, Error* error)
+  IndexMappings CreateIndexMappings(const Configuration configuration, const Mappings source, const Mappings target, Error* error)
   {
     DeleteError(error);
     std::size_t size = configuration.data_->size();