diff -up adns-1.5.1/src/event.c.me adns-1.5.1/src/event.c
diff -up adns-1.5.1/src/internal.h.me adns-1.5.1/src/internal.h
--- adns-1.5.1/src/internal.h.me	2020-02-18 13:54:38.578415675 +0100
+++ adns-1.5.1/src/internal.h	2020-02-18 14:00:26.398198338 +0100
@@ -246,7 +246,9 @@ union maxalign {
   void *p;
   void (*fp)(void);
   union maxalign *up;
-} data;
+};
+
+extern union maxalign data;
 
 struct adns__query {
   adns_state ads;