diff --git a/send.py b/send.py
index 4bacfa1..b4ba2f1 100755
--- a/send.py
+++ b/send.py
@@ -27,25 +27,28 @@ sym = Symbol()
 class Writer(object):
     def __init__(self):
         self.last = time.time()
+        self.offset = 0
 
     def write(self, fd, sym, n=1):
-        fd.write(common.dumps(sym, n))
+        data = common.dumps(sym, n)
+        fd.write(data)
+        self.offset += len(data)
         if time.time() > self.last + 1:
             log.debug('%10.3f seconds of data audio',
-                      fd.tell() / wave.bytes_per_second)
+                      self.offset / wave.bytes_per_second)
             self.last += 1
 
-write = Writer().write
+writer = Writer()
 
 
 def start(fd, c):
-    write(fd, c*1, n=400)
-    write(fd, c*0, n=50)
+    writer.write(fd, c*1, n=400)
+    writer.write(fd, c*0, n=50)
 
 
 def training(fd, c):
     for b in train.equalizer:
-        write(fd, c * b)
+        writer.write(fd, c * b)
 
 
 def modulate(fd, bits):
@@ -55,7 +58,7 @@ def modulate(fd, bits):
     while True:
         symbols = itertools.islice(symbols_iter, len(sym.carrier))
         symbols = np.array(list(symbols))
-        write(fd, np.dot(symbols, carriers))
+        writer.write(fd, np.dot(symbols, carriers))
         if all(symbols == 0):  # EOF marker
             break
 
@@ -85,12 +88,12 @@ def main(args):
     fd = sys.stdout
 
     # padding audio with silence
-    write(fd, np.zeros(int(config.Fs * args.silence_start)))
+    writer.write(fd, np.zeros(int(config.Fs * args.silence_start)))
 
     start(fd, sym.carrier[config.carrier_index])
     for c in sym.carrier:
         training(fd, c)
-    training_size = fd.tell()
+    training_size = writer.offset
     log.info('%.3f seconds of training audio',
              training_size / wave.bytes_per_second)
 
@@ -99,12 +102,12 @@ def main(args):
     encoded = itertools.chain.from_iterable(ecc.encode(data))
     modulate(fd, bits=common.to_bits(encoded))
 
-    data_size = fd.tell() - training_size
+    data_size = writer.offset - training_size
     log.info('%.3f seconds of data audio, for %.3f kB of data',
              data_size / wave.bytes_per_second, reader.total / 1e3)
 
     # padding audio with silence
-    write(fd, np.zeros(int(config.Fs * args.silence_stop)))
+    writer.write(fd, np.zeros(int(config.Fs * args.silence_stop)))
 
 if __name__ == '__main__':
     logging.basicConfig(level=logging.DEBUG,