diff --git a/lib/dns/ipkeylist.c b/lib/dns/ipkeylist.c
index 2a123e0466..c70c1dc837 100644
--- a/lib/dns/ipkeylist.c
+++ b/lib/dns/ipkeylist.c
@@ -16,6 +16,8 @@
 
 #include <config.h>
 
+#include <string.h>
+
 #include <isc/mem.h>
 #include <isc/sockaddr.h>
 #include <isc/util.h>