diff --git a/src/WebSocketExtensions.h b/src/WebSocketExtensions.h
index e03cd63..9368ec9 100644
--- a/src/WebSocketExtensions.h
+++ b/src/WebSocketExtensions.h
@@ -18,6 +18,7 @@
 #ifndef UWS_WEBSOCKETEXTENSIONS_H
 #define UWS_WEBSOCKETEXTENSIONS_H
 
+#include <climits>
 #include <string_view>
 
 namespace uWS {