diff --git a/test/normalized_argument_types.cpp b/test/normalized_argument_types.cpp
index 7685da9..5a7266f 100644
--- a/test/normalized_argument_types.cpp
+++ b/test/normalized_argument_types.cpp
@@ -4,6 +4,7 @@
 // http://www.boost.org/LICENSE_1_0.txt)
 
 #include <boost/parameter/config.hpp>
+#include <cstddef>
 
 #if (BOOST_PARAMETER_MAX_ARITY < 2)
 #error Define BOOST_PARAMETER_MAX_ARITY as 2 or greater.