diff --git a/include/boost/mpi/collectives/reduce.hpp b/include/boost/mpi/collectives/reduce.hpp
index 4a94d71..1e2722e 100644
--- a/include/boost/mpi/collectives/reduce.hpp
+++ b/include/boost/mpi/collectives/reduce.hpp
@@ -46,7 +46,7 @@ namespace detail {
   template<typename T, typename Op>
   void
   reduce_impl(const communicator& comm, const T* in_values, int n,
-              T* out_values, Op op, int root, mpl::true_ /*is_mpi_op*/,
+              T* out_values, Op /*op*/, int root, mpl::true_ /*is_mpi_op*/,
               mpl::true_/*is_mpi_datatype*/)
   {
     BOOST_MPI_CHECK_RESULT(MPI_Reduce,
@@ -59,7 +59,7 @@ namespace detail {
   // datatype and operation, so we'll use MPI_Reduce directly.
   template<typename T, typename Op>
   void
-  reduce_impl(const communicator& comm, const T* in_values, int n, Op op,
+  reduce_impl(const communicator& comm, const T* in_values, int n, Op /*op*/,
               int root, mpl::true_ /*is_mpi_op*/, mpl::true_/*is_mpi_datatype*/)
   {
     BOOST_MPI_CHECK_RESULT(MPI_Reduce,
diff --git a/include/boost/mpi/collectives/scan.hpp b/include/boost/mpi/collectives/scan.hpp
index 4cba4a8..9264838 100644
--- a/include/boost/mpi/collectives/scan.hpp
+++ b/include/boost/mpi/collectives/scan.hpp
@@ -47,7 +47,7 @@ namespace detail {
   template<typename T, typename Op>
   void
   scan_impl(const communicator& comm, const T* in_values, int n, T* out_values,
-            Op op, mpl::true_ /*is_mpi_op*/, mpl::true_ /*is_mpi_datatype*/)
+            Op /*op*/, mpl::true_ /*is_mpi_op*/, mpl::true_ /*is_mpi_datatype*/)
   {
     BOOST_MPI_CHECK_RESULT(MPI_Scan,
                            (const_cast<T*>(in_values), out_values, n,
diff --git a/include/boost/mpi/detail/forward_skeleton_iarchive.hpp b/include/boost/mpi/detail/forward_skeleton_iarchive.hpp
index c4b9e0f..0dfcaf9 100644
--- a/include/boost/mpi/detail/forward_skeleton_iarchive.hpp
+++ b/include/boost/mpi/detail/forward_skeleton_iarchive.hpp
@@ -61,10 +61,10 @@ BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(archive::tracking_type)
 BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(archive::class_name_type)
 BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(serialization::collection_size_type)
 
-    void load_override(std::string & s , int)    
+    void load_override(std::string & s)    
     {                            
       serialization::collection_size_type length(s.size());              
-      load_override(length,0);       
+      load_override(length);       
       s.resize(length);
     }
 
diff --git a/include/boost/mpi/detail/forward_skeleton_oarchive.hpp b/include/boost/mpi/detail/forward_skeleton_oarchive.hpp
index 4b0e057..1a170b4 100644
--- a/include/boost/mpi/detail/forward_skeleton_oarchive.hpp
+++ b/include/boost/mpi/detail/forward_skeleton_oarchive.hpp
@@ -61,9 +61,9 @@ BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(archive::tracking_type)
 BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(archive::class_name_type)
 BOOST_ARCHIVE_FORWARD_IMPLEMENTATION(serialization::collection_size_type)
 
-    void save_override(std::string const & t , int)    
+    void save_override(std::string const & t)    
     {                                          
-      save_override(serialization::collection_size_type(t.size()),0);       
+      save_override(serialization::collection_size_type(t.size()));       
     }
 
 
diff --git a/include/boost/mpi/detail/ignore_skeleton_oarchive.hpp b/include/boost/mpi/detail/ignore_skeleton_oarchive.hpp
index 29248f9..f9285a2 100644
--- a/include/boost/mpi/detail/ignore_skeleton_oarchive.hpp
+++ b/include/boost/mpi/detail/ignore_skeleton_oarchive.hpp
@@ -58,10 +58,10 @@ BOOST_ARCHIVE_IGNORE_IMPLEMENTATION(archive::class_name_type)
 BOOST_ARCHIVE_IGNORE_IMPLEMENTATION(serialization::collection_size_type)
 BOOST_ARCHIVE_IGNORE_IMPLEMENTATION(serialization::item_version_type)
 
-    void save_override(std::string const & s, int)       
+    void save_override(std::string const & s)       
     {
       if (s.size())
-        save_override(serialization::make_array(s.data(),s.size()),0);
+        save_override(serialization::make_array(s.data(),s.size()));
     }
 
 #undef BOOST_ARCHIVE_IGNORE_IMPLEMENTATION