diff --git a/disassembler.cpp b/disassembler.cpp
index efd61ce..d24b35e 100644
--- a/disassembler.cpp
+++ b/disassembler.cpp
@@ -1,3 +1,5 @@
+#define _XOPEN_SOURCE
+
 #include "disassembler.h"
 #include <stdio.h>
 #include <string.h>