diff --git a/build/config/Linux b/build/config/Linux
index 39bdc8e81..40ef8f059 100644
--- a/build/config/Linux
+++ b/build/config/Linux
@@ -69,7 +69,7 @@ RELEASEOPT_LINK = -O2
 #
 # System Specific Flags
 #
-SYSFLAGS = -D_XOPEN_SOURCE=500 -D_REENTRANT -D_THREAD_SAFE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -DPOCO_HAVE_FD_EPOLL -DPOCO_HAVE_ADDRINFO -DPOCO_HAVE_LIBRESOLV
+SYSFLAGS = -D_XOPEN_SOURCE=600 -D_REENTRANT -D_THREAD_SAFE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -DPOCO_HAVE_FD_EPOLL -DPOCO_HAVE_ADDRINFO -DPOCO_HAVE_LIBRESOLV
 
 #
 # System Specific Libraries