diff --git a/tools/regression/netinet/tcpfullwindowrst/tcpfullwindowrsttest.c b/tools/regression/netinet/tcpfullwindowrst/tcpfullwindowrsttest.c
index ac86b9e7627..6e4ac0356a3 100644
--- a/tools/regression/netinet/tcpfullwindowrst/tcpfullwindowrsttest.c
+++ b/tools/regression/netinet/tcpfullwindowrst/tcpfullwindowrsttest.c
@@ -35,6 +35,7 @@ $FreeBSD$
 #include <poll.h>
 #include <unistd.h>
 #include <signal.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>