Index: src/include/watchdog/wd_utils.h
--- src/include/watchdog/wd_utils.h.orig
+++ src/include/watchdog/wd_utils.h
@@ -26,6 +26,7 @@
 #define WD_UTILS_H
 
 #include <ifaddrs.h>
+#include <pthread.h>
 #include "parser/pg_list.h"
 
 #define WD_NG (0)
