diff --git a/amodem/audio.py b/amodem/audio.py
index 63a734a..e5ebb71 100644
--- a/amodem/audio.py
+++ b/amodem/audio.py
@@ -4,6 +4,7 @@ import functools
 
 log = logging.getLogger(__name__)
 
+
 class ALSA(object):
     def __init__(self, tool, Fs):
         self.Fs = int(Fs)  # sampling rate
diff --git a/amodem/calib.py b/amodem/calib.py
index 484f88b..b58e4ab 100644
--- a/amodem/calib.py
+++ b/amodem/calib.py
@@ -82,6 +82,7 @@ def run_recorder(config, recorder):
 fmt = '{freq:6.0f} Hz: {message:s}{extra:s}'
 fields = ['peak', 'total', 'rms', 'coherency']
 
+
 def recv(config, audio_record=audio.record, verbose=False):
     extra = ''
     if verbose:
diff --git a/amodem/config.py b/amodem/config.py
index 02a4b32..8213269 100644
--- a/amodem/config.py
+++ b/amodem/config.py
@@ -32,7 +32,8 @@ class Configuration(object):
         # QAM constellation
         Nx = 2 ** int(np.ceil(bits_per_symbol / 2))
         Ny = self.Npoints // Nx
-        symbols = np.array([complex(x, y) for x in range(Nx) for y in range(Ny)])
+        symbols = [complex(x, y) for x in range(Nx) for y in range(Ny)]
+        symbols = np.array(symbols)
         symbols = symbols - symbols[-1]/2
         self.symbols = symbols / np.max(np.abs(symbols))
 
diff --git a/amodem/dsp.py b/amodem/dsp.py
index e2f5fb9..a8c963f 100644
--- a/amodem/dsp.py
+++ b/amodem/dsp.py
@@ -130,7 +130,7 @@ class MODEM(object):
         self.symbols = symbols
         self.bits_per_symbol = bits_per_symbol
 
-        bits_map = dict((symbol, bits) for bits, symbol in self.encode_map.items())
+        bits_map = dict(item[::-1] for item in self.encode_map.items())
         self.decode_list = [(s, bits_map[s]) for s in self.symbols]
 
     def encode(self, bits):
diff --git a/amodem/equalizer.py b/amodem/equalizer.py
index c1b4930..da85920 100644
--- a/amodem/equalizer.py
+++ b/amodem/equalizer.py
@@ -9,6 +9,7 @@ import random
 
 _constellation = [1, 1j, -1, -1j]
 
+
 class Equalizer(object):
 
     def __init__(self, config):
@@ -22,7 +23,6 @@ class Equalizer(object):
         choose = lambda: [r.choice(_constellation) for j in range(self.Nfreq)]
         return np.array([choose() for i in range(length)])
 
-
     def modulator(self, symbols):
         gain = 1.0 / len(self.carriers)
         result = []
@@ -65,7 +65,8 @@ class Equalizer(object):
         return h
 
     def equalize_signal(self, signal, expected, order, lookahead=0):
-        signal = np.concatenate([np.zeros(order-1), signal, np.zeros(lookahead)])
+        signal = [np.zeros(order-1), signal, np.zeros(lookahead)]
+        signal = np.concatenate(signal)
         length = len(expected)
 
         A = []
diff --git a/amodem/recv.py b/amodem/recv.py
index 8d5ee6c..ccb2181 100644
--- a/amodem/recv.py
+++ b/amodem/recv.py
@@ -154,7 +154,7 @@ class Receiver(object):
 
     def start(self, signal, gain=1.0):
         sampler = sampling.Sampler(signal, sampling.Interpolator())
-        symbols = dsp.Demux(sampler=sampler, omegas=self.omegas, Nsym=self.Nsym)
+        symbols = dsp.Demux(sampler, omegas=self.omegas, Nsym=self.Nsym)
         freq_err = self._prefix(symbols, gain=gain)
         sampler.freq -= freq_err
 
diff --git a/amodem/send.py b/amodem/send.py
index ef6b8ba..865236d 100644
--- a/amodem/send.py
+++ b/amodem/send.py
@@ -12,6 +12,7 @@ from . import framing
 from . import equalizer
 from . import dsp
 
+
 class Sender(object):
     def __init__(self, fd, config):
         self.offset = 0
@@ -50,6 +51,7 @@ class Sender(object):
                 total_bits = i * Nfreq * self.modem.bits_per_symbol
                 log.debug('Sent %8.1f kB', total_bits / 8e3)
 
+
 def main(args):
     sender = Sender(args.output, config=args.config)
     Fs = args.config.Fs
@@ -70,7 +72,7 @@ def main(args):
 
     data_duration = sender.offset - training_duration
     log.info('Sent %.3f kB @ %.3f seconds',
-        reader.total / 1e3, data_duration / Fs)
+             reader.total / 1e3, data_duration / Fs)
 
     # post-padding audio with silence
     sender.write(np.zeros(int(Fs * args.silence_stop)))