diff --git a/httplib.h b/httplib.h
index c7449cd..82d9f3a 100644
--- a/httplib.h
+++ b/httplib.h
@@ -9213,7 +9213,7 @@ inline Client::Client(const std::string &scheme_host_port,
                       const std::string &client_cert_path,
                       const std::string &client_key_path) {
   const static std::regex re(
-      R"((?:([a-z]+):\/\/)?(?:\[([\d:]+)\]|([^:/?#]+))(?::(\d+))?)");
+      R"((?:([a-z]+):\/\/)?(?:\[([a-fA-F\d:]+)\]|([^:/?#]+))(?::(\d+))?)");
 
   std::smatch m;
   if (std::regex_match(scheme_host_port, m, re)) {