diff --git a/tests/serialize/test_codecs.py b/tests/serialize/test_codecs.py
index b6177d591..280b4d1a5 100644
--- a/tests/serialize/test_codecs.py
+++ b/tests/serialize/test_codecs.py
@@ -16,7 +16,8 @@ def test_binary():
     msg = numpy.array([0, 1, 0, 1, 1], numpy.int32)
     codec.encode(msg, bits)
     result = numpy.array([0, 0, 0, 0, 0], numpy.int32)
-    codec.decode(iter(bits), result)
+    bits.seek(0)
+    codec.decode(bits, result)
     assert list(msg) == list(result)
 
 
@@ -35,6 +36,7 @@ def test_attribute():
     msg_list = list(msg)
     codec.encode(msg, bits)
     result = numpy.array([0, 0], dtype=numpy.int32)
+    bits.seek(0)
     codec.decode(bits, result)
     assert msg_list == list(result)
 
@@ -69,5 +71,6 @@ def test_vocab_codec():
     msg_list = list(msg)
     codec.encode(msg, bits)
     result = numpy.array(range(len(msg)), dtype=numpy.int32)
+    bits.seek(0)
     codec.decode(bits, result)
     assert msg_list == list(result)
diff --git a/tests/serialize/test_huffman.py b/tests/serialize/test_huffman.py
index 188ebbc58..4cdac8f0c 100644
--- a/tests/serialize/test_huffman.py
+++ b/tests/serialize/test_huffman.py
@@ -13,7 +13,6 @@ from collections import defaultdict
 
 class MockPacker(object):
     def __init__(self, freqs):
-        freqs['-eol-'] = 5
         total = sum(freqs.values())
         by_freq = freqs.items()
         by_freq.sort(key=lambda item: item[1], reverse=True)
@@ -24,13 +23,14 @@ class MockPacker(object):
 
     def pack(self, message):
         seq = [self.table[sym] for sym in message]
-        msg = numpy.array(seq, dtype=numpy.uint32)
+        msg = numpy.array(seq, dtype=numpy.int32)
         bits = BitArray()
         self.codec.encode(msg, bits)
         return bits
 
     def unpack(self, bits, n):
-        msg = numpy.array(range(n), dtype=numpy.uint32)
+        msg = numpy.array(range(n), dtype=numpy.int32)
+        bits.seek(0)
         self.codec.decode(bits, msg)
         return [self.symbols[i] for i in msg]