diff --git a/jerry-core/jrt/jrt.h b/jerry-core/jrt/jrt.h
index b947fc5fd..46ab6b203 100644
--- a/jerry-core/jrt/jrt.h
+++ b/jerry-core/jrt/jrt.h
@@ -16,8 +16,11 @@
 #ifndef JRT_H
 #define JRT_H
 
+#if !defined (_XOPEN_SOURCE) || _XOPEN_SOURCE < 500
+#undef _XOPEN_SOURCE
 /* Required macro for sleep functions (nanosleep or usleep) */
 #define _XOPEN_SOURCE 500
+#endif
 
 #include <stdio.h>
 #include <string.h>