diff --git a/src/elfhacks.cpp b/src/elfhacks.cpp
index 48ebfe6d..eaf3342a 100644
--- a/src/elfhacks.cpp
+++ b/src/elfhacks.cpp
@@ -19,6 +19,11 @@
 #include <fnmatch.h>
 #include "elfhacks.h"
 
+#ifndef __ELF_NATIVE_CLASS
+#include "sys/reg.h"
+#define __ELF_NATIVE_CLASS __WORDSIZE
+#endif
+
 /**
  *  \addtogroup elfhacks
  *  \{