diff --git a/libtransmission/announcer-udp.c b/libtransmission/announcer-udp.c
index d9b106fb7..d83fc62a9 100644
--- a/libtransmission/announcer-udp.c
+++ b/libtransmission/announcer-udp.c
@@ -12,6 +12,7 @@
 
 #define __LIBTRANSMISSION_ANNOUNCER_MODULE___
 
+#include <errno.h> /* errno, EAFNOSUPPORT */
 #include <string.h> /* memcpy (), memset () */
 
 #include <event2/buffer.h>