diff --git a/src/user_filter.cpp b/src/user_filter.cpp
index ee49e95..bd11b52 100644
--- a/src/user_filter.cpp
+++ b/src/user_filter.cpp
@@ -9,12 +9,12 @@ void UserFilter<set_body_flag, require_admin>::doFilter(const HttpRequestPtr &re
                                                         FilterChainCallback &&fccb)
 {
     std::string_view auth_header = req->getHeader("Authorization");
-    if (auth_header.size() > 6 && auth_header.size() <= 517) //"Basic " + username + ':' + password
+    if (auth_header.size() > 6 && auth_header.size() <= 688) //"Basic " + (username + ':' + password) * 4/3
     {
         if (auth_header.substr(0, 6) == "Basic ")
         {
             std::string_view base64_input = auth_header.substr(6);
-            std::array<char, 384> base64_result; //(255 username + ':' + 255 password) * 3/4
+            std::array<char, 511> base64_result; //(255 username + ':' + 255 password) 
             size_t new_sz;
             base64_decode(base64_input.data(), base64_input.size(), base64_result.begin(), &new_sz, 0);