--- raptor/src/raptor2.h.in.orig	2016-08-26 23:45:34.543400074 +0200
+++ raptor/src/raptor2.h.in	2016-08-26 23:45:40.479399614 +0200
@@ -2176,6 +2176,7 @@
 void* raptor_avltree_iterator_get(raptor_avltree_iterator* iterator);
 
 /* utility methods */
+RAPTOR_API
 void raptor_sort_r(void *base, size_t nel, size_t width, raptor_data_compare_arg_handler compar, void *user_data);