diff --git a/python/caca/canvas.py b/python/caca/canvas.py
index 9426480..d69baa6 100644
--- a/python/caca/canvas.py
+++ b/python/caca/canvas.py
@@ -25,13 +25,12 @@ from caca.font import _Font
 class _CanvasStruct(ctypes.Structure):
     pass
 
-
 class _Canvas(object):
     """ Model for Canvas objects.
     """
 
     def __init__(self):
-        self._cv = 0
+        self._cv = None
 
     def from_param(self):
         """ Required by ctypes module to call object as parameter of
@@ -43,7 +42,7 @@ class _Canvas(object):
         return "<CacaCanvas %dx%d>" % (self.get_width(), self.get_height())
 
     def __del__(self):
-        if self._cv > 0 and _lib is not None:
+        if self._cv and _lib is not None:
             self._free()
 
     def _free(self):
diff --git a/python/caca/display.py b/python/caca/display.py
index 5d9a8d9..25a4873 100644
--- a/python/caca/display.py
+++ b/python/caca/display.py
@@ -19,6 +19,7 @@ import ctypes
 from caca import _lib, _PYTHON3, _str_to_bytes
 from caca.canvas import _Canvas, Canvas
 
+
 class _DisplayStruct(ctypes.Structure):
     pass
 
@@ -36,7 +37,7 @@ class _Display(object):
         return "<CacaDisplay>"
 
     def __del__(self):
-        if self._dp > 0 and _lib is not None:
+        if self._dp and _lib is not None:
             self._free()
 
     def _free(self):
@@ -205,9 +206,11 @@ class Display(_Display):
 
         return _lib.caca_get_mouse_y(self)
 
+
 class DisplayError(Exception):
     pass
 
+
 class Event(ctypes.Structure):
     """ Object to store libcaca event.
     """
diff --git a/python/caca/dither.py b/python/caca/dither.py
index 8a0e60f..d423289 100644
--- a/python/caca/dither.py
+++ b/python/caca/dither.py
@@ -27,7 +27,7 @@ class _Dither(object):
     """ Model for Dither object.
     """
     def __init__(self):
-        self._dither = 0
+        self._dither = None
 
     def from_param(self):
         """ Required by ctypes module to call object as parameter of
@@ -36,7 +36,7 @@ class _Dither(object):
         return self._dither
 
     def __del__(self):
-        if self._dither > 0:
+        if self._dither:
             self._free()
 
     def __str__(self):
diff --git a/python/caca/font.py b/python/caca/font.py
index fc66f8a..a04cc8e 100644
--- a/python/caca/font.py
+++ b/python/caca/font.py
@@ -27,7 +27,7 @@ class _Font(object):
     """ Model for Font object.
     """
     def __init__(self):
-        self._font = 0
+        self._font = None
 
     def from_param(self):
         """ Required by ctypes module to call object as parameter of
@@ -37,7 +37,7 @@ class _Font(object):
 
     def __del__(self):
         if hasattr(self, "_font"):
-            if self._font > 0:
+            if self._font:
                 self._free()
 
     def __str__(self):