diff --git a/contrib/libcxxrt/cxxabi.h b/contrib/libcxxrt/cxxabi.h
index 4b661b640c14..7c8336076bb0 100644
--- a/contrib/libcxxrt/cxxabi.h
+++ b/contrib/libcxxrt/cxxabi.h
@@ -22,6 +22,7 @@
 
 #ifndef __CXXABI_H_
 #define __CXXABI_H_
+#include <stddef.h>
 #include <stdint.h>
 #include "unwind.h"
 namespace std