diff --git a/faster_whisper/audio.py b/faster_whisper/audio.py
index 1f1970aa..9e98d179 100644
--- a/faster_whisper/audio.py
+++ b/faster_whisper/audio.py
@@ -53,7 +53,7 @@ def decode_audio(
         for frame in frames:
             array = frame.to_ndarray()
             dtype = array.dtype
-            raw_buffer.write(array)
+            raw_buffer.write(array.tobytes())
 
     # It appears that some objects related to the resampler are not freed
     # unless the garbage collector is manually run.