--- a/tests/join0.c
+++ b/tests/join0.c
@@ -58,7 +58,7 @@
   /* Create a single thread and wait for it to exit. */
   assert(pthread_create(&id, NULL, func, (void *) 123) == 0);
 
-  assert(pthread_join(id, (void *) &result) == 0);
+  assert(pthread_join(id, &result) == 0);
 
   assert((int)(size_t)result == 123);