diff --git a/pyModeS/adsb.py b/pyModeS/adsb.py
index a777c72..3ac99b7 100644
--- a/pyModeS/adsb.py
+++ b/pyModeS/adsb.py
@@ -17,8 +17,9 @@
 A python package for decoding ABS-D messages.
 """
 
+from __future__ import absolute_import, print_function, division
 import math
-import util
+from . import util
 
 
 def df(msg):
diff --git a/pyModeS/ehs.py b/pyModeS/ehs.py
index 29ae828..a30cc0c 100644
--- a/pyModeS/ehs.py
+++ b/pyModeS/ehs.py
@@ -17,9 +17,8 @@
 A python package for decoding ModeS (DF20, DF21) messages.
 """
 
-import util
-from util import crc
-
+from __future__ import absolute_import, print_function, division
+from . import util
 
 def df(msg):
     """Get the downlink format (DF) number
@@ -53,7 +52,7 @@ def icao(msg):
         # raise RuntimeError("Message DF must be in (4, 5, 20, 21)")
         return None
 
-    c0 = util.bin2int(crc(msg, encode=True))
+    c0 = util.bin2int(util.crc(msg, encode=True))
     c1 = util.hex2int(msg[-6:])
     icao = '%06X' % (c0 ^ c1)
     return icao
diff --git a/tests/sample_data_test.py b/tests/sample_data_test.py
index 5a2a67b..a18f95c 100644
--- a/tests/sample_data_test.py
+++ b/tests/sample_data_test.py
@@ -1,6 +1,4 @@
-import os, sys
-sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))+'/pyModeS')
-import adsb, ehs, util
+from pyModeS import adsb, ehs, util
 
 
 # === Decode sample data file ===
diff --git a/tests/test_adsb.py b/tests/test_adsb.py
index 3fb0f82..9bb759e 100644
--- a/tests/test_adsb.py
+++ b/tests/test_adsb.py
@@ -1,6 +1,4 @@
-import os, sys
-sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))+'/pyModeS')
-import adsb
+from pyModeS import adsb
 
 # === TEST ADS-B package ===
 
diff --git a/tests/test_ehs.py b/tests/test_ehs.py
index 737879a..cc84f95 100644
--- a/tests/test_ehs.py
+++ b/tests/test_ehs.py
@@ -1,6 +1,4 @@
-import os, sys
-sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))+'/pyModeS')
-import ehs
+from pyModeS import ehs
 
 
 def test_ehs_icao():
diff --git a/tests/test_util.py b/tests/test_util.py
index d2a6704..d4cc6e3 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -1,6 +1,4 @@
-import os, sys
-sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))+'/pyModeS')
-import util
+from pyModeS import util
 
 
 def test_hex2bin():