diff --git a/amodem/calib.py b/amodem/calib.py
index 53446b7..25e0643 100755
--- a/amodem/calib.py
+++ b/amodem/calib.py
@@ -1,9 +1,10 @@
 #!/usr/bin/env python
 import numpy as np
-import common
-import config
-import sigproc
-import wave
+
+from . import common
+from . import config
+from . import sigproc
+from . import wave
 
 Tsample = 1
 t = np.arange(int(Tsample * config.Fs)) * config.Ts
diff --git a/amodem/common.py b/amodem/common.py
index 97b58a6..62791e2 100644
--- a/amodem/common.py
+++ b/amodem/common.py
@@ -108,3 +108,9 @@ def icapture(iterable, result):
 
 def take(iterable, n):
     return np.array(list(itertools.islice(iterable, n)))
+
+
+try:
+    izip = itertools.izip
+except AttributeError:
+    izip = zip  # Python 3
diff --git a/amodem/ecc.py b/amodem/ecc.py
index b80b1aa..f69445c 100644
--- a/amodem/ecc.py
+++ b/amodem/ecc.py
@@ -1,7 +1,7 @@
 ''' Reed-Solomon CODEC. '''
 from reedsolo import rs_encode_msg, rs_correct_msg
 
-import common
+from . import common
 
 import logging
 log = logging.getLogger(__name__)
diff --git a/amodem/loop.py b/amodem/loop.py
index a1a409e..beef6cb 100644
--- a/amodem/loop.py
+++ b/amodem/loop.py
@@ -1,8 +1,9 @@
 import numpy as np
 import itertools
 
-import sampling
-import sigproc
+from . import sampling
+from . import sigproc
+from . import common
 
 
 class Filter(object):
@@ -33,4 +34,4 @@ class FreqLoop(object):
             self.gens.append(gen)
 
     def __iter__(self):
-        return itertools.izip(*self.gens)
+        return common.izip(*self.gens)
diff --git a/amodem/recv.py b/amodem/recv.py
index d1d95ad..d6596df 100755
--- a/amodem/recv.py
+++ b/amodem/recv.py
@@ -8,21 +8,24 @@ import time
 import sys
 import os
 
+import bitarray
+
 log = logging.getLogger(__name__)
 
-import stream
-import sigproc
-import loop
-import train
-import common
-import config
+from . import stream
+from . import sigproc
+from . import loop
+from . import train
+from . import common
+from . import config
+from . import ecc
 
 modem = sigproc.MODEM(config)
 
 
 if os.environ.get('PYLAB') == '1':
-    import pylab
-    import show
+    from . import pylab
+    from . import show
     WIDTH = np.floor(np.sqrt(len(modem.freqs)))
     HEIGHT = np.ceil(len(modem.freqs) / float(WIDTH))
 else:
@@ -223,9 +226,6 @@ def receive(signal, freqs, gain=1.0):
 
 
 def decode(bits_iterator):
-    import bitarray
-    import ecc
-
     def blocks():
         while True:
             bits = itertools.islice(bits_iterator, 8 * ecc.BLOCK_SIZE)
diff --git a/amodem/send.py b/amodem/send.py
index cae52d2..8f60210 100755
--- a/amodem/send.py
+++ b/amodem/send.py
@@ -7,13 +7,14 @@ import time
 
 log = logging.getLogger(__name__)
 
-import train
-import wave
+from . import train
+from . import wave
 
-import common
-import config
-import sigproc
-import stream
+from . import common
+from . import config
+from . import sigproc
+from . import stream
+from . import ecc
 
 modem = sigproc.MODEM(config)
 
@@ -66,7 +67,6 @@ def modulate(fd, bits):
 
 
 def main(args):
-    import ecc
     log.info('Running MODEM @ {:.1f} kbps'.format(modem.modem_bps / 1e3))
 
     # padding audio with silence
diff --git a/amodem/sigproc.py b/amodem/sigproc.py
index 270c1fb..91b8f33 100644
--- a/amodem/sigproc.py
+++ b/amodem/sigproc.py
@@ -1,8 +1,8 @@
 import numpy as np
 from numpy import linalg
 
-import common
-from config import Ts, Nsym
+from . import common
+from .config import Ts, Nsym
 
 
 class Filter(object):
diff --git a/amodem/stream.py b/amodem/stream.py
index 78ff5eb..20123d5 100644
--- a/amodem/stream.py
+++ b/amodem/stream.py
@@ -1,6 +1,5 @@
 import time
 
-import wave
 
 
 class Reader(object):
diff --git a/amodem/wave.py b/amodem/wave.py
index 57e47ab..7ab4a98 100755
--- a/amodem/wave.py
+++ b/amodem/wave.py
@@ -6,7 +6,7 @@ import logging
 
 log = logging.getLogger(__name__)
 
-import config
+from . import config
 Fs = int(config.Fs)  # sampling rate
 
 bits_per_sample = 16
diff --git a/tests/test_full.py b/tests/test_full.py
index 564e8af..6fcd276 100644
--- a/tests/test_full.py
+++ b/tests/test_full.py
@@ -1,5 +1,9 @@
 import os
-from cStringIO import StringIO
+try:
+    from cStringIO import StringIO as BytesIO
+except ImportError:
+    from io import BytesIO  # Python 3
+
 import numpy as np
 
 from amodem import send