diff --git a/contrib/pg_upgrade/server.c b/contrib/pg_upgrade/server.c
index e86540b9d79..a4c2b6d50d1 100644
--- a/contrib/pg_upgrade/server.c
+++ b/contrib/pg_upgrade/server.c
@@ -144,9 +144,10 @@ start_postmaster(ClusterInfo *cluster)
 {
 	char		cmd[MAXPGPATH];
 	PGconn	   *conn;
-	bool		exit_hook_registered = false;
 	int			pg_ctl_return = 0;
 
+	static bool exit_hook_registered = false;
+
 #ifndef WIN32
 	char	   *output_filename = log_opts.filename;
 #else