diff --git a/lib/dns/ncache.c b/lib/dns/ncache.c
index e371d35dda..5d5a13afd4 100644
--- a/lib/dns/ncache.c
+++ b/lib/dns/ncache.c
@@ -17,6 +17,7 @@
 
 #include <config.h>
 
+#include <isc/buffer.h>
 #include <isc/util.h>
 
 #include <dns/db.h>