diff --git a/bin/dig/nslookup.c b/bin/dig/nslookup.c
index 7acd811270..beb8efd7db 100644
--- a/bin/dig/nslookup.c
+++ b/bin/dig/nslookup.c
@@ -48,6 +48,9 @@
 #elif defined(HAVE_READLINE_READLINE_H)
 /* Prevent deprecated functions being declared. */
 #define _FUNCTION_DEF 1
+/* Ensure rl_message() gets prototype. */
+#define USE_VARARGS   1
+#define PREFER_STDARG 1
 #include <readline/readline.h>
 #if defined(HAVE_READLINE_HISTORY_H)
 #include <readline/history.h>
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index b0d00ebc9f..d8f2011d6b 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -95,6 +95,9 @@
 #else /* if defined(HAVE_EDIT_READLINE_READLINE_H) */
 /* Prevent deprecated functions being declared. */
 #define _FUNCTION_DEF 1
+/* Ensure rl_message() gets prototype. */
+#define USE_VARARGS   1
+#define PREFER_STDARG 1
 #include <readline/history.h>
 #include <readline/readline.h>
 #endif /* if defined(HAVE_EDIT_READLINE_READLINE_H) */