diff --git a/lib/dns/nxt.c b/lib/dns/nxt.c
index ed8645acd6..679f9ab402 100644
--- a/lib/dns/nxt.c
+++ b/lib/dns/nxt.c
@@ -17,6 +17,8 @@
 
 #include <config.h>
 
+#include <string.h>
+
 #include <isc/assertions.h>
 
 #include <dns/types.h>