The library docs say *** newForeignPtr :: ... ...Note that there is no guarantee on how soon the finalizer is executed after the last reference was dropped; this depends on the details of the Haskell storage manager. The only guarantee is that the finalizer runs before the program terminates. *** As others have noted too, there is in fact *no* guarantee that finalizers are called. The only way I found to force calling of finalizers is explicitly calling System.Mem.performGC before the program exits. Is this a bug in the implementation of finalizers or is the documentation wrong or am I just stupid? Ben -- Top level things with identity are evil. -- Lennart Augustsson