diff --git a/libao/libao-ffi.rkt b/libao/libao-ffi.rkt
index c37c1c8..6688176 100644
--- a/libao/libao-ffi.rkt
+++ b/libao/libao-ffi.rkt
@@ -68,7 +68,7 @@
 (define-libao ao_close (_fun _libao-pointer -> _int))
 
 ; void ao_shutdown();
-(define-libao ao_shutdown (_fun -> _int))
+(define-libao ao_shutdown (_fun -> _void))
 
 ; int ao_append_option(ao_option **options, const char *key, const char *value);
 (define-libao ao_append_option (_fun _pointer _pointer _pointer -> _int))
diff --git a/libflac/libflac-ffi.rkt b/libflac/libflac-ffi.rkt
index 677e4f3..d5b5020 100644
--- a/libflac/libflac-ffi.rkt
+++ b/libflac/libflac-ffi.rkt
@@ -402,7 +402,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define _FLAC__StreamDecoder-pointer (_cpointer 'flac-streamdecoder))
-(define _FLAC__Data-pointer (_cpointer 'flac-client-data))
+(define _FLAC__Data-pointer (_cpointer/null 'flac-client-data))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; FLAC Callback function definitions
@@ -414,18 +414,21 @@
   (_fun _FLAC__StreamDecoder-pointer
         _FLAC__Frame-pointer
         FLAC__int32** 
-        _FLAC__Data-pointer -> _int))
+        _FLAC__Data-pointer
+        -> _int))
 
 ;typedef void(* FLAC__StreamDecoderMetadataCallback) (const FLAC__StreamDecoder *decoder, const FLAC__StreamMetadata *metadata, void *client_data)
 (define _FLAC__StreamDecoderMetadataCallback
   (_fun _FLAC__StreamDecoder-pointer
         _FLAC__StreamMetadata-pointer
-        _FLAC__Data-pointer -> _void))
+        _FLAC__Data-pointer
+        -> _void))
 
 (define _FLAC__StreamDecoderErrorCallback
   (_fun _FLAC__StreamDecoder-pointer
         _int
-        _FLAC__Data-pointer -> _void))
+        _FLAC__Data-pointer
+        -> _void))
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -464,6 +467,7 @@
         _FLAC__StreamDecoderWriteCallback
         _FLAC__StreamDecoderMetadataCallback
         _FLAC__StreamDecoderErrorCallback
+        _FLAC__Data-pointer  ; Seen by Jens Axel Søgaard - Is already present in FLAC 1.4.3 
         -> _int))
 
 (define-libflac FLAC__stream_decoder_process_single
@@ -488,15 +492,16 @@
   (define error-no -1)
   (define fl #f)
   (define flac-file #f)
+  (define client-data #f)
   
-  (define (write-callback fl frame buffer data)
+  (define (write-callback fl frame buffer client-data)
     (set! write-data (append write-data (list (cons frame buffer))))
     0)
 
-  (define (meta-callback fl meta data)
+  (define (meta-callback fl meta client-data)
     (set! meta-data (append meta-data (list meta))))
 
-  (define (error-callback fl errno data)
+  (define (error-callback fl errno client-data)
     (set! error-no errno)
     )
 
@@ -506,11 +511,12 @@
 
   (define (init file)
     (let ((r (FLAC__stream_decoder_init_file
-             fl
-             file
-             write-callback
-             meta-callback
-             error-callback)))
+              fl
+              file
+              write-callback
+              meta-callback
+              error-callback
+              client-data)))
       (set! flac-file file)
       r))
 
diff --git a/play-test.rkt b/play-test.rkt
index ae2304b..257a30b 100644
--- a/play-test.rkt
+++ b/play-test.rkt
@@ -15,6 +15,7 @@
     )
   )
 
+(ao-set-async-mode! 'scheme)
 ;(define fmt (ao-mk-format 24 48000 2 'big-endian))
 ;(define ao-h (ao-open-live #f fmt))
 
@@ -34,7 +35,7 @@
     (when (eq? ao-h #f)
       (let ((fmt (ao-mk-format bits-per-sample rate channels 'big-endian)))
         (set! ao-h (ao-open-live #f fmt))))
-    (ao-play ao-h second buffer)
+    (ao-play ao-h second duration buffer)
     (let ((second-printer (λ ()
                             (let ((s (inexact->exact (round (ao-at-second ao-h)))))
                               (unless (= s current-seconds)