diff --git a/src/apfl.h b/src/apfl.h
index b4ff64e..4ed11ce 100644
--- a/src/apfl.h
+++ b/src/apfl.h
@@ -554,24 +554,6 @@ void apfl_editable_dict_destroy(apfl_editable_dict);
  */
 apfl_dict apfl_editable_dict_finalize(apfl_editable_dict);
 
-enum apfl_function_response_type {
-    APFL_FUNCTION_RESPONSE_OK,
-    APFL_FUNCTION_RESPONSE_ERROR,
-};
-
-struct apfl_function_response {
-    enum apfl_function_response_type type;
-    struct apfl_value value;
-};
-
-typedef struct apfl_function_response (*apfl_user_function_cb)(apfl_ctx, struct apfl_list arguments, void *);
-
-struct apfl_user_function {
-    apfl_user_function_cb cb;
-    void *opaque;
-};
-
-
 enum apfl_result_type {
     APFL_RESULT_OK,
     APFL_RESULT_ERR,