diff --git a/include/boost/mpi/collectives/all_gather.hpp b/include/boost/mpi/collectives/all_gather.hpp
index fd4f00a..cd467a9 100644
--- a/include/boost/mpi/collectives/all_gather.hpp
+++ b/include/boost/mpi/collectives/all_gather.hpp
@@ -46,7 +46,6 @@ void
 all_gather_impl(const communicator& comm, const T* in_values, int n, 
                 T* out_values, int const* sizes, int const* skips, mpl::false_)
 {
-  int tag = environment::collectives_tag();
   int nproc = comm.size();
   // first, gather all size, these size can be different for
   // each process
diff --git a/include/boost/mpi/collectives/all_gatherv.hpp b/include/boost/mpi/collectives/all_gatherv.hpp
index c979d6d..d62cc7b 100644
--- a/include/boost/mpi/collectives/all_gatherv.hpp
+++ b/include/boost/mpi/collectives/all_gatherv.hpp
@@ -78,7 +78,7 @@ void
 all_gatherv(const communicator& comm, const T* in_values, T* out_values,
             const std::vector<int>& sizes)
 {
-  assert(sizes.size()   == comm.size());
+  assert(int(sizes.size()) == comm.size());
   detail::all_gatherv_impl(comm, in_values, out_values, sizes.data(), 0, is_mpi_datatype<T>());
 }
 
@@ -87,8 +87,8 @@ void
 all_gatherv(const communicator& comm, std::vector<T> const& in_values,  std::vector<T>& out_values,
            const std::vector<int>& sizes)
 {
-  assert(sizes.size()   == comm.size());
-  assert(in_values.size() == sizes[comm.rank()]);
+  assert(int(sizes.size()) == comm.size());
+  assert(int(in_values.size()) == sizes[comm.rank()]);
   out_values.resize(std::accumulate(sizes.begin(), sizes.end(), 0));
   ::boost::mpi::all_gatherv(comm, in_values.data(), out_values.data(), sizes);
 }
@@ -125,7 +125,7 @@ all_gatherv(const communicator& comm, std::vector<T> const& in_values, std::vect
   assert(displs.size() == comm.size());
   assert(in_values.size() == sizes[comm.rank()]);
   out_values.resize(std::accumulate(sizes.begin(), sizes.end(), 0));
-  ::boost::mpi::all_gatherv(comm, in_values.data(), out_values.data(), sizes, displs)
+  ::boost::mpi::all_gatherv(comm, in_values.data(), out_values.data(), sizes, displs);
 }
 
 } } // end namespace boost::mpi
diff --git a/include/boost/mpi/collectives/gather.hpp b/include/boost/mpi/collectives/gather.hpp
index 5943a22..6ebfda5 100644
--- a/include/boost/mpi/collectives/gather.hpp
+++ b/include/boost/mpi/collectives/gather.hpp
@@ -57,7 +57,6 @@ void
 gather_impl(const communicator& comm, const T* in_values, int n, T* out_values, 
             int const* nslot, int const* nskip, int root, mpl::false_)
 {
-  int tag = environment::collectives_tag();
   int nproc = comm.size();
   // first, gather all size, these size can be different for
   // each process
diff --git a/include/boost/mpi/collectives/scatterv.hpp b/include/boost/mpi/collectives/scatterv.hpp
index c8e286c..eb9f41d 100644
--- a/include/boost/mpi/collectives/scatterv.hpp
+++ b/include/boost/mpi/collectives/scatterv.hpp
@@ -99,7 +99,7 @@ scatterv(const communicator& comm, const T* in_values,
          const std::vector<int>& sizes, const std::vector<int>& displs,
          T* out_values, int out_size, int root)
 {
-  scatterv_impl(comm, in_values, out_values, out_sizes, sizes.data(), displs.data(), 
+  scatterv_impl(comm, in_values, out_values, out_size, sizes.data(), displs.data(), 
                 root, is_mpi_datatype<T>());
 }
 
@@ -146,7 +146,7 @@ void
 scatterv(const communicator& comm, const T* in_values,
          T* out_values, int n, int root)
 {
-  detail::scatterv_impl(comm, in_values, out_values, out_sizes, sizes.data(), (it const*)0,
+  detail::scatterv_impl(comm, in_values, out_values, n, (int const*)0, (int const*)0,
                 root, is_mpi_datatype<T>());
 }