diff --git a/client_https.hpp b/client_https.hpp
index dfc4d8f..e5c59ef 100644
--- a/client_https.hpp
+++ b/client_https.hpp
@@ -95,7 +95,7 @@ namespace SimpleWeb {
                     io_service.run();
                     
                     auto response=request_read();
-                    if (response->status_code.empty() || response->status_code.substr(0,3) != "200") {
+                    if (response->status_code.empty() || response->status_code.compare(0, 3, "200") != 0) {
                         std::lock_guard<std::mutex> lock(socket_mutex);
                         socket=nullptr;
                         throw boost::system::system_error(boost::system::error_code(boost::system::errc::permission_denied, boost::system::generic_category()));
diff --git a/server_http.hpp b/server_http.hpp
index 6970bc0..ee0f31f 100644
--- a/server_http.hpp
+++ b/server_http.hpp
@@ -304,7 +304,7 @@ namespace SimpleWeb {
 
                     size_t protocol_end;
                     if((protocol_end=line.find('/', path_end+1))!=std::string::npos) {
-                        if(line.substr(path_end+1, protocol_end-path_end-1)!="HTTP")
+                        if(line.compare(path_end+1, protocol_end-path_end-1, "HTTP")!=0)
                             return false;
                         request->http_version=line.substr(protocol_end+1, line.size()-protocol_end-2);
                     }