diff --git a/libs/openzap/src/include/openzap.h b/libs/openzap/src/include/openzap.h
index 03f58b6da0..48cffda0be 100644
--- a/libs/openzap/src/include/openzap.h
+++ b/libs/openzap/src/include/openzap.h
@@ -35,7 +35,7 @@
 #define OPENZAP_H
 
 
-#ifndef _XOPEN_SOURCE
+#if !defined(_XOPEN_SOURCE) && !defined(__FreeBSD__)
 #define _XOPEN_SOURCE 600
 #endif