X-Git-Url: https://git.tcpdump.org/libpcap/blobdiff_plain/b1f597f914be77473ed685e0f0361a7f1d31cb0f..refs/heads/master:/ftmacros.h

diff --git a/ftmacros.h b/ftmacros.h
index a1488e12..2e367a35 100644
--- a/ftmacros.h
+++ b/ftmacros.h
@@ -100,8 +100,12 @@
    * We don't limit this to, for example, Linux and Cygwin, because
    * this might, for example, be GNU/HURD or one of Debian's kFreeBSD
    * OSes ("GNU/FreeBSD").
+   *
+   * Avoid redefining, same as below.
    */
-  #define _GNU_SOURCE
+  #ifndef _GNU_SOURCE
+    #define _GNU_SOURCE
+  #endif
 
   /*
    * We turn on both _DEFAULT_SOURCE and _BSD_SOURCE to try to get