diff --git a/src/saslplugin/plugin_common.c b/src/saslplugin/plugin_common.c
index 524f4de..a022704 100644
--- a/src/saslplugin/plugin_common.c
+++ b/src/saslplugin/plugin_common.c
@@ -51,7 +51,9 @@
 # include <sys/socket.h>
 # include <netinet/in.h>
 # include <arpa/inet.h>
+# define _GNU_SOURCE
 # include <netdb.h>
+# undef _GNU_SOURCE
 # include <sys/utsname.h>
 #endif /* WIN32 */
 #endif /* macintosh */