diff --git a/asio_compatibility.hpp b/asio_compatibility.hpp
index dc08653..aa43451 100644
--- a/asio_compatibility.hpp
+++ b/asio_compatibility.hpp
@@ -27,12 +27,12 @@ namespace SimpleWeb {
 #endif
 
 namespace SimpleWeb {
-#if(ASIO_STANDALONE && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
+#if(defined(ASIO_STANDALONE) && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
   using io_context = asio::io_context;
   using resolver_results = asio::ip::tcp::resolver::results_type;
   using async_connect_endpoint = asio::ip::tcp::endpoint;
 
-#if(ASIO_STANDALONE && ASIO_VERSION >= 101800) || BOOST_ASIO_VERSION >= 101800
+#if(defined(ASIO_STANDALONE) && ASIO_VERSION >= 101800) || BOOST_ASIO_VERSION >= 101800
   using strand = asio::strand<asio::any_io_executor>;
 #else
   using strand = asio::strand<asio::executor>;
diff --git a/client_https.hpp b/client_https.hpp
index 9458723..86c042c 100644
--- a/client_https.hpp
+++ b/client_https.hpp
@@ -27,7 +27,7 @@ namespace SimpleWeb {
     Client(const std::string &server_port_path, bool verify_certificate = true, const std::string &certification_file = std::string(),
            const std::string &private_key_file = std::string(), const std::string &verify_file = std::string())
         : ClientBase<HTTPS>::ClientBase(server_port_path, 443),
-#if(ASIO_STANDALONE && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
+#if(defined(ASIO_STANDALONE) && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
           context(asio::ssl::context::tls_client) {
       // Disabling TLS 1.0 and 1.1 (see RFC 8996)
       context.set_options(asio::ssl::context::no_tlsv1);
diff --git a/server_https.hpp b/server_https.hpp
index 67b8491..9b77fdc 100644
--- a/server_https.hpp
+++ b/server_https.hpp
@@ -29,7 +29,7 @@ namespace SimpleWeb {
      */
     Server(const std::string &certification_file, const std::string &private_key_file, const std::string &verify_file = std::string())
         : ServerBase<HTTPS>::ServerBase(443),
-#if(ASIO_STANDALONE && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
+#if(defined(ASIO_STANDALONE) && ASIO_VERSION >= 101300) || BOOST_ASIO_VERSION >= 101300
           context(asio::ssl::context::tls_server) {
       // Disabling TLS 1.0 and 1.1 (see RFC 8996)
       context.set_options(asio::ssl::context::no_tlsv1);