diff --git a/include/boost/mpi/collectives/all_reduce.hpp b/include/boost/mpi/collectives/all_reduce.hpp
index 9a62d3b..26b8fc9 100644
--- a/include/boost/mpi/collectives/all_reduce.hpp
+++ b/include/boost/mpi/collectives/all_reduce.hpp
@@ -33,7 +33,7 @@ namespace detail {
     BOOST_MPI_CHECK_RESULT(MPI_Allreduce,
                            (const_cast<T*>(in_values), out_values, n,
                             boost::mpi::get_mpi_datatype<T>(*in_values),
-                            is_mpi_op<Op, T>::op(), comm));
+                            (is_mpi_op<Op, T>::op()), comm));
   }
 
   /**********************************************************************
diff --git a/include/boost/mpi/collectives/reduce.hpp b/include/boost/mpi/collectives/reduce.hpp
index 6ea8279..f1dee82 100644
--- a/include/boost/mpi/collectives/reduce.hpp
+++ b/include/boost/mpi/collectives/reduce.hpp
@@ -52,7 +52,7 @@ namespace detail {
     BOOST_MPI_CHECK_RESULT(MPI_Reduce,
                            (const_cast<T*>(in_values), out_values, n,
                             boost::mpi::get_mpi_datatype<T>(*in_values),
-                            is_mpi_op<Op, T>::op(), root, comm));
+                            (is_mpi_op<Op, T>::op()), root, comm));
   }
 
   // We are reducing to the root for a type that has an associated MPI
@@ -65,7 +65,7 @@ namespace detail {
     BOOST_MPI_CHECK_RESULT(MPI_Reduce,
                            (const_cast<T*>(in_values), 0, n,
                             boost::mpi::get_mpi_datatype<T>(*in_values),
-                            is_mpi_op<Op, T>::op(), root, comm));
+                            (is_mpi_op<Op, T>::op()), root, comm));
   }
 
   /**********************************************************************
diff --git a/include/boost/mpi/collectives/scan.hpp b/include/boost/mpi/collectives/scan.hpp
index 83dc8ca..4cba4a8 100644
--- a/include/boost/mpi/collectives/scan.hpp
+++ b/include/boost/mpi/collectives/scan.hpp
@@ -52,7 +52,7 @@ namespace detail {
     BOOST_MPI_CHECK_RESULT(MPI_Scan,
                            (const_cast<T*>(in_values), out_values, n,
                             boost::mpi::get_mpi_datatype<T>(*in_values),
-                            is_mpi_op<Op, T>::op(), comm));
+                            (is_mpi_op<Op, T>::op()), comm));
   }
 
   /**********************************************************************
diff --git a/include/boost/mpi/detail/mpi_datatype_cache.hpp b/include/boost/mpi/detail/mpi_datatype_cache.hpp
index cc073e2..c99ddb1 100644
--- a/include/boost/mpi/detail/mpi_datatype_cache.hpp
+++ b/include/boost/mpi/detail/mpi_datatype_cache.hpp
@@ -88,7 +88,7 @@ private:
 };
 
 /// Retrieve the MPI datatype cache
-mpi_datatype_map& mpi_datatype_cache();
+BOOST_MPI_DECL mpi_datatype_map& mpi_datatype_cache();
 
 } } } // end namespace boost::mpi::detail