diff --git a/.gitignore b/.gitignore
index 20e1433..c3e6d97 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,6 @@ io_test
 parse_test
 crypto_test
 status_code_test
+
+# Visual Studio 2015/2017 cache/options directory
+.vs/
diff --git a/.vs/ProjectSettings.json b/.vs/ProjectSettings.json
deleted file mode 100644
index 899f460..0000000
--- a/.vs/ProjectSettings.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "CurrentProjectSetting": "x86-Debug"
-}
\ No newline at end of file
diff --git a/.vs/Simple-Web-Server/v15/Browse.VC.db b/.vs/Simple-Web-Server/v15/Browse.VC.db
deleted file mode 100644
index 833baed..0000000
Binary files a/.vs/Simple-Web-Server/v15/Browse.VC.db and /dev/null differ
diff --git a/.vs/Simple-Web-Server/v15/Browse.VC.opendb b/.vs/Simple-Web-Server/v15/Browse.VC.opendb
deleted file mode 100644
index 0188e62..0000000
Binary files a/.vs/Simple-Web-Server/v15/Browse.VC.opendb and /dev/null differ
diff --git a/.vs/slnx.sqlite b/.vs/slnx.sqlite
deleted file mode 100644
index 1d49f8f..0000000
Binary files a/.vs/slnx.sqlite and /dev/null differ
diff --git a/client_http.hpp b/client_http.hpp
index 0832d38..4cec9a7 100644
--- a/client_http.hpp
+++ b/client_http.hpp
@@ -16,16 +16,6 @@ namespace SimpleWeb {
   using errc = std::errc;
   using system_error = std::system_error;
   namespace make_error_code = std;
-#ifdef __has_include 
-  #if __has_include(<string_view>)
-    #include<string_view>
-    using string_view = std::string_view;
-    #define __has_string_view 1
-  #endif
-#endif
-#ifndef __has_string_view
-  using string_view = const std::string &;
-#endif
 } // namespace SimpleWeb
 #else
 #include <boost/asio.hpp>
@@ -37,10 +27,19 @@ namespace SimpleWeb {
   namespace errc = boost::system::errc;
   using system_error = boost::system::system_error;
   namespace make_error_code = boost::system::errc;
-  using string_view = boost::string_ref;
 } // namespace SimpleWeb
 #endif
 
+#if defined(__has_include) && __has_include(<string_view>)
+#include <string_view>
+namespace SimpleWeb { using string_view = std::string_view; }
+#elif !defined(USE_STANDALONE_ASIO)
+#include <boost/utility/string_ref.hpp>
+namespace SimpleWeb { using string_view = boost::string_ref; }  
+#else
+namespace SimpleWeb { using string_view = const std::string &; }
+#endif
+
 namespace SimpleWeb {
   template <class socket_type>
   class Client;