diff --git a/httplib.h b/httplib.h
index 0f981dc..9af65a3 100644
--- a/httplib.h
+++ b/httplib.h
@@ -6055,6 +6055,10 @@ inline void calc_actual_timeout(time_t max_timeout_msec, time_t duration_msec,
   auto actual_timeout_msec =
       (std::min)(max_timeout_msec - duration_msec, timeout_msec);
 
+  if (actual_timeout_msec < 0) {
+    actual_timeout_msec = 0;
+  }
+
   actual_timeout_sec = actual_timeout_msec / 1000;
   actual_timeout_usec = (actual_timeout_msec % 1000) * 1000;
 }