diff --git a/src/hci/readline.c b/src/hci/readline.c
index 7df8b6bb..ff7a7679 100644
--- a/src/hci/readline.c
+++ b/src/hci/readline.c
@@ -32,6 +32,8 @@
 
 #define READLINE_MAX 256
 
+static void sync_console ( struct edit_string *string ) __nonnull;
+
 /**
  * Synchronise console with edited string
  *