diff --git a/dansguardian/src/authplugins/ntlm.cpp b/dansguardian/src/authplugins/ntlm.cpp
index 8fc2982..b95fa06 100644
--- a/dansguardian/src/authplugins/ntlm.cpp
+++ b/dansguardian/src/authplugins/ntlm.cpp
@@ -23,6 +23,7 @@
 	#include "dgconfig.h"
 #endif
 
+#include <stddef.h>
 #include "../Auth.hpp"
 #include "../FDTunnel.hpp"
 #include "../OptionContainer.hpp"