diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index a773e3f..f371905 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -4,6 +4,22 @@ Change Log
 
 Notable project changes in various releases.
 
+
+1.5
+===
+
+Added
+-----
+
+* mpifx_win allows allocations with 64 bit allocation size parameter
+
+
+Changed
+-------
+
+* mpifx_win is fully standard conforming now (using the F08 MPI-interface)
+
+
 1.4
 ===
 
diff --git a/README.rst b/README.rst
index c6119e1..43540f4 100644
--- a/README.rst
+++ b/README.rst
@@ -3,7 +3,7 @@ MpiFx - Modern Fortran Interface for MPI
 ****************************************
 
 The open source library `MpiFx <https://github.com/dftbplus/mpifx>`_ provides
-modern Fortran (Fortran 2003) wrappers around routines of the MPI library to
+modern Fortran (Fortran 2008) wrappers around routines of the MPI library to
 make their use as simple as possible. Currently several data distribution
 routines are covered.
 
@@ -14,14 +14,36 @@ The documentation is included inside the repository, but is also available at
 Installation
 ============
 
+The preferred way of obtaining MpiFx is to install it via the Conda package
+management framework using `Miniconda
+<https://docs.conda.io/en/latest/miniconda.html>`_ or `Anaconda
+<https://www.anaconda.com/products/individual>`_. Make sure to add/enable the
+``conda-forge`` channel in order to be able to access MpiFx, and ensure that the
+``conda-forge`` channel is the first repository to be searched for packages.
+
+We provide both, OpenMPI and MPICH based build variants, choose the one suiting
+your needs. For example, issue ::
+
+  conda install 'mpifx=*=mpi_mpich_*'
+
+or ::
+
+  conda install 'mpifx=*=mpi_openmpi_*'
+
+to get the last stable release of MpiFx for the respective MPI framework.
+
+
+Building from source
+====================
+
 Prerequisites
 -------------
 
 * CMake (version >= 3.16)
 
-* Fortran 2003 compatible Fortran compiler
+* Fortran 2008 compatible Fortran compiler
 
-* MPI-library and wrappers for your compiler
+* MPI-library and wrappers for your compiler supporting the `mpi_f08` interface
 
 * `Fypp preprocessor <https://github.com/aradi/fypp>`_
 
@@ -40,7 +62,7 @@ You can influence the configuration via CMake-variables, which are listed in
 or pass them as command line options at the configuration phase, e.g.::
 
   FC=ifort cmake -B _build -DBUILD_TESTING=NO .
-  
+
 
 Testing
 -------
@@ -61,15 +83,15 @@ CMake build
 * Make sure to add the root folder of the installed library to the
   ``CMAKE_PREFIX_PATH`` environment variable.
 
-* Use ``find_package()`` in `CMakeLists.txt` to locate the library and link 
+* Use ``find_package()`` in `CMakeLists.txt` to locate the library and link
   ``MpiFx::MpiFx`` to every target which relies directly on the library ::
 
     cmake_minimum_required(VERSION 3.16)
-   
+
     project(TestMpiFx LANGUAGES Fortran)
-    
+
     find_package(MpiFx REQUIRED)
-    
+
     add_executable(test_mpifx test_mpifx.f90)
     target_link_libraries(test_mpifx MpiFx::MpiFx)
 
diff --git a/lib/mpifx_constants.fpp b/lib/mpifx_constants.fpp
index 48ff532..35391d5 100644
--- a/lib/mpifx_constants.fpp
+++ b/lib/mpifx_constants.fpp
@@ -19,6 +19,7 @@ module mpifx_constants_module
   !> Exit code for failed assertions
   integer, parameter :: MPIFX_ASSERT_FAILED = 2
 
+  !> Native integer for MPI addresses
   integer, parameter :: MPIFX_SIZE_T = MPI_ADDRESS_KIND
 
 end module mpifx_constants_module
diff --git a/lib/mpifx_get_processor_name.fpp b/lib/mpifx_get_processor_name.fpp
index 4b0fb8f..577dc91 100644
--- a/lib/mpifx_get_processor_name.fpp
+++ b/lib/mpifx_get_processor_name.fpp
@@ -1,6 +1,7 @@
 !> Contains the extended MPI communicator.
 module mpifx_get_processor_name_module
   use mpi
+  use mpifx_helper_module, only : handle_errorflag
   implicit none
   private
 
diff --git a/lib/mpifx_recv.fpp b/lib/mpifx_recv.fpp
index 6f5f681..3ce0523 100644
--- a/lib/mpifx_recv.fpp
+++ b/lib/mpifx_recv.fpp
@@ -6,7 +6,7 @@
 module mpifx_recv_module
   use mpi
   use mpifx_comm_module, only : mpifx_comm
-  use mpifx_helper_module, only : dp, sp
+  use mpifx_helper_module, only : dp, sp, getoptarg, handle_errorflag, setoptarg
   implicit none
   private
 
diff --git a/lib/mpifx_send.fpp b/lib/mpifx_send.fpp
index 4459795..aae2569 100644
--- a/lib/mpifx_send.fpp
+++ b/lib/mpifx_send.fpp
@@ -6,7 +6,7 @@
 module mpifx_send_module
   use mpi
   use mpifx_comm_module, only : mpifx_comm
-  use mpifx_helper_module, only : default_tag, dp, sp
+  use mpifx_helper_module, only : default_tag, dp, sp, getoptarg, handle_errorflag
   implicit none
   private
 
diff --git a/lib/mpifx_win.fpp b/lib/mpifx_win.fpp
index e85e711..1e4b301 100644
--- a/lib/mpifx_win.fpp
+++ b/lib/mpifx_win.fpp
@@ -4,7 +4,9 @@
 
 !> Contains routined for MPI shared memory windows.
 module mpifx_win_module
-  use mpi_f08
+  use mpi_f08, only : MPI_ADDRESS_KIND, mpi_barrier, mpi_comm, MPI_INFO_NULL, MPI_MODE_NOCHECK,&
+      & mpi_win, mpi_win_allocate_shared, mpi_win_fence, mpi_win_free, mpi_win_lock_all,&
+      & mpi_win_shared_query, mpi_win_sync, mpi_win_unlock
   use mpifx_helper_module, only : handle_errorflag, sp, dp
   use mpifx_comm_module, only : mpifx_comm
   use mpifx_constants_module, only : MPIFX_SIZE_T