--- posix-spawn-0.3.15.orig/ext/posix-spawn.c
+++ posix-spawn-0.3.15/ext/posix-spawn.c
@@ -223,7 +223,7 @@
 posixspawn_file_actions_init(posix_spawn_file_actions_t *fops, VALUE options)
 {
 	posix_spawn_file_actions_init(fops);
-	rb_hash_foreach(options, posixspawn_file_actions_operations_iter, (VALUE)fops);
+	rb_hash_foreach(options, (void *) posixspawn_file_actions_operations_iter, (VALUE)fops);
 }
 
 /*