diff --git a/usr.sbin/ypldap/ldapclient.c b/usr.sbin/ypldap/ldapclient.c
index e95585aaad3..897ceb2b090 100644
--- a/usr.sbin/ypldap/ldapclient.c
+++ b/usr.sbin/ypldap/ldapclient.c
@@ -34,6 +34,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <pwd.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>