diff --git a/moviepy/audio/io/ffmpeg_audiowriter.py b/moviepy/audio/io/ffmpeg_audiowriter.py
index e895f5d80..dfa3a1eb0 100644
--- a/moviepy/audio/io/ffmpeg_audiowriter.py
+++ b/moviepy/audio/io/ffmpeg_audiowriter.py
@@ -84,7 +84,7 @@ def write_frames(self,frames_array):
         try:
             self.proc.stdin.write(frames_array.tostring())
         except IOError as err:
-            ffmpeg_error = self.proc.stderr.read()
+            ffmpeg_error = str(self.proc.stderr.read())
             error = (str(err)+ ("\n\nMoviePy error: FFMPEG encountered "
                      "the following error while writing file %s:"%self.filename
                      + "\n\n"+ffmpeg_error))
diff --git a/moviepy/video/io/ffmpeg_writer.py b/moviepy/video/io/ffmpeg_writer.py
index 605015206..8d0837f6d 100644
--- a/moviepy/video/io/ffmpeg_writer.py
+++ b/moviepy/video/io/ffmpeg_writer.py
@@ -136,7 +136,7 @@ def write_frame(self, img_array):
         try:
             self.proc.stdin.write(img_array.tostring())
         except IOError as err:
-            ffmpeg_error = self.proc.stderr.read()
+            ffmpeg_error = str(self.proc.stderr.read())
             error = (str(err) + ("\n\nMoviePy error: FFMPEG encountered "
                                  "the following error while writing file %s:"
                                  "\n\n %s" % (self.filename, ffmpeg_error)))