diff --git a/pyModeS/ehs.py b/pyModeS/ehs.py
index 92f0867..dd813f5 100644
--- a/pyModeS/ehs.py
+++ b/pyModeS/ehs.py
@@ -336,7 +336,7 @@ def isBDS44(msg, rev=False):
         # Bits 1-4 are reserved and should be zero
         if util.bin2int(d[0:4]) != 0:
             result &= False
-        
+
     if not result:
         return False
 
@@ -794,7 +794,7 @@ def vr53(msg):
     if d[46] == '0':
         return None
 
-    sign = d[47]    # 1 -> minus
+    sign = int(d[47])    # 1 -> minus
     value = util.bin2int(d[48:56])
 
     if sign:
@@ -925,7 +925,7 @@ def vr60baro(msg):
     if d[34] == '0':
         return None
 
-    sign = d[35]    # 1 -> minus
+    sign = int(d[35])    # 1 -> minus
     value = util.bin2int(d[36:45])
 
     if sign:
@@ -949,7 +949,7 @@ def vr60ins(msg):
     if d[45] == '0':
         return None
 
-    sign = d[46]    # 1 -> minus
+    sign = int(d[46])    # 1 -> minus
     value = util.bin2int(d[47:56])
 
     if sign:
diff --git a/tox.ini b/tox.ini
index 8ab7582..ed3f701 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 toxworkdir=/tmp/tox
-envlist = py26,py27,py35
+envlist = py2,py3
 [testenv]
 deps=pytest
 commands=py.test