diff -up abook-0.6.1/database.h.orig abook-0.6.1/database.h
--- abook-0.6.1/database.h.orig	2015-10-04 04:38:25.000000000 +0200
+++ abook-0.6.1/database.h	2025-01-09 12:40:15.733159868 +0100
@@ -61,7 +61,7 @@ struct db_enumerator {
 /*
  * Field operations
  */
-inline int field_id(int i);
+extern inline int field_id(int i);
 abook_field *find_standard_field(char *key, int do_declare);
 abook_field *real_find_field(char *key, abook_field_list *list, int *nb);
 #define find_field(key, list)		real_find_field(key, list, NULL)