diff --git a/json_object.c b/json_object.c
index c3974a0..cc4c1e2 100644
--- a/json_object.c
+++ b/json_object.c
@@ -53,6 +53,7 @@
 #endif
 #endif
 
+const char *json_number_chars = "0123456789.+-eE"; /* Unused, but part of public API, drop for 1.0 */
 const char *json_hex_chars = "0123456789abcdefABCDEF";
 
 static void json_object_generic_delete(struct json_object *jso);