diff --git a/include/boost/interprocess/detail/os_file_functions.hpp b/include/boost/interprocess/detail/os_file_functions.hpp
index 95e5d9c..692eb07 100644
--- a/include/boost/interprocess/detail/os_file_functions.hpp
+++ b/include/boost/interprocess/detail/os_file_functions.hpp
@@ -126,11 +126,11 @@ inline bool get_temporary_path(char *buffer, std::size_t buf_len, std::size_t &r
    required_len = 0;
    //std::size_t is always bigger or equal than unsigned long in Windows systems
    //In case std::size_t is bigger than unsigned long
-   unsigned long buf = buf_len;
-   if(buf_len != buf){   //maybe overflowed
+   unsigned long ulbuflen = static_cast<unsigned long>(buf_len); //Potentially losing convertion in 64 bits
+   if(buf_len != ulbuflen){   //maybe overflowed
       return false;
    }
-   required_len = winapi::get_temp_path(buf_len, buffer);
+   required_len = winapi::get_temp_path(ulbuflen, buffer);
    const bool ret = required_len && (buf_len > required_len);
    if(ret && buffer[required_len-1] == '\\'){
       buffer[required_len-1] = '\0';
@@ -143,11 +143,11 @@ inline bool get_temporary_path(wchar_t *buffer, std::size_t buf_len, std::size_t
    required_len = 0;
    //std::size_t is always bigger or equal than unsigned long in Windows systems
    //In case std::size_t is bigger than unsigned long
-   unsigned long buf = buf_len;
-   if(buf_len != buf){   //maybe overflowed
+   unsigned long ulbuflen = static_cast<unsigned long>(buf_len); //Potentially losing convertion in 64 bits
+   if(buf_len != ulbuflen){   //maybe overflowed
       return false;
    }
-   required_len = winapi::get_temp_path(buf_len, buffer);
+   required_len = winapi::get_temp_path(ulbuflen, buffer);
    const bool ret = !(buf_len < required_len);
    if(ret && buffer[required_len-1] == L'\\'){
       buffer[required_len-1] = L'\0';
@@ -225,7 +225,7 @@ inline bool truncate_file (file_handle_t hnd, std::size_t size)
       }
    }
    else{
-      if(!winapi::set_file_pointer(hnd, size, 0, winapi::file_begin)){
+      if(!winapi::set_file_pointer(hnd, static_cast<unsigned long>(size), 0, winapi::file_begin)){
          return false;
       }
       if(!winapi::set_end_of_file(hnd)){
diff --git a/include/boost/interprocess/detail/win32_api.hpp b/include/boost/interprocess/detail/win32_api.hpp
index 2c8bb7b..44b770d 100644
--- a/include/boost/interprocess/detail/win32_api.hpp
+++ b/include/boost/interprocess/detail/win32_api.hpp
@@ -1243,8 +1243,8 @@ class nt_query_mem_deleter
       (SystemTimeOfDayInfoLength + sizeof(unsigned long) + sizeof(boost::winapi::DWORD_))*2;
 
    public:
-   explicit nt_query_mem_deleter(std::size_t object_name_info_size)
-      : m_size(object_name_info_size + rename_offset + rename_suffix)
+   explicit nt_query_mem_deleter(unsigned long object_name_info_size)
+      : m_size(static_cast<unsigned long>(object_name_info_size + rename_offset + rename_suffix))
       , m_buf(new char [m_size])
    {}
 
@@ -1270,7 +1270,7 @@ class nt_query_mem_deleter
       return static_cast<unsigned long>(m_size - rename_offset - SystemTimeOfDayInfoLength*2);
    }
 
-   std::size_t file_rename_information_size() const
+   unsigned long file_rename_information_size() const
    {  return static_cast<unsigned long>(m_size);  }
 
    private:
@@ -1444,7 +1444,7 @@ inline bool get_registry_value_buffer(hkey key_type, const CharT *subkey_name, c
       reg_closer key_closer(key);
 
       //Obtain the value
-      unsigned long size = buflen;
+      unsigned long size = static_cast<unsigned long>(buflen);
       unsigned long type;
       buflen = 0;
       bret = 0 == reg_query_value_ex( key, value_name, 0, &type, (unsigned char*)buf, &size);
diff --git a/include/boost/interprocess/mapped_region.hpp b/include/boost/interprocess/mapped_region.hpp
index 1ef2845..0871a72 100644
--- a/include/boost/interprocess/mapped_region.hpp
+++ b/include/boost/interprocess/mapped_region.hpp
@@ -477,7 +477,7 @@ inline mapped_region::mapped_region
                                  (native_mapping_handle,
                                  map_access,
                                  ::boost::ulong_long_type(offset - page_offset),
-                                 static_cast<std::size_t>(page_offset + size),
+                                 static_cast<std::size_t>(page_offset) + size,
                                  const_cast<void*>(address));
       //Check error
       if(!base){
diff --git a/include/boost/interprocess/sync/windows/named_sync.hpp b/include/boost/interprocess/sync/windows/named_sync.hpp
index eed1229..1e960fd 100644
--- a/include/boost/interprocess/sync/windows/named_sync.hpp
+++ b/include/boost/interprocess/sync/windows/named_sync.hpp
@@ -81,7 +81,7 @@ inline windows_named_sync::windows_named_sync()
 
 inline void windows_named_sync::close(windows_named_sync_interface &sync_interface)
 {
-   const std::size_t buflen = sync_interface.get_data_size();
+   const unsigned long buflen = static_cast<unsigned long>(sync_interface.get_data_size());
    winapi::interprocess_overlapped overlapped;
    if(winapi::lock_file_ex
       (m_file_hnd, winapi::lockfile_exclusive_lock, 0, 1, 0, &overlapped)){
@@ -129,7 +129,7 @@ inline void windows_named_sync::open_or_create
       bool success = false;
       if(m_file_hnd != winapi::invalid_handle_value){
          //Now lock the file
-         const std::size_t buflen = sync_interface.get_data_size();
+         const unsigned long buflen = static_cast<unsigned long>(sync_interface.get_data_size());
          typedef __int64 unique_id_type;
          const std::size_t sizeof_file_info = sizeof(unique_id_type) + buflen;
          winapi::interprocess_overlapped overlapped;