diff --git a/ixwebsocket/libwshandshake.hpp b/ixwebsocket/libwshandshake.hpp
index fbe098b5..c048e38b 100644
--- a/ixwebsocket/libwshandshake.hpp
+++ b/ixwebsocket/libwshandshake.hpp
@@ -21,6 +21,7 @@
 #include <cstdint>
 #include <cstddef>
 #include <string>
+#include <string.h>
 
 class WebSocketHandshakeKeyGen {
     template <int N, typename T>