diff --git a/lib/isc/inet_ntop.c b/lib/isc/inet_ntop.c
index 64ad577e0b..a63f0587da 100644
--- a/lib/isc/inet_ntop.c
+++ b/lib/isc/inet_ntop.c
@@ -22,6 +22,7 @@ static char rcsid[] =
 #include <isc/net.h>
 #include <isc/print.h>
 #include <isc/string.h>
+#include <isc/util.h>
 
 #define NS_INT16SZ	 2
 #define NS_IN6ADDRSZ	16