diff --git a/babel/messages/pofile.py b/babel/messages/pofile.py
index b94274df2..00e084447 100644
--- a/babel/messages/pofile.py
+++ b/babel/messages/pofile.py
@@ -92,11 +92,9 @@ def append(self, s):
     def denormalize(self):
         return ''.join(map(unescape, self._strs))
 
-    def __nonzero__(self):
+    def __bool__(self):
         return bool(self._strs)
 
-    __bool__ = __nonzero__
-
     def __repr__(self):
         return os.linesep.join(self._strs)
 
diff --git a/babel/support.py b/babel/support.py
index dbd914e4a..e11a9954f 100644
--- a/babel/support.py
+++ b/babel/support.py
@@ -192,7 +192,7 @@ def value(self):
     def __contains__(self, key):
         return key in self.value
 
-    def __nonzero__(self):
+    def __bool__(self):
         return bool(self.value)
 
     def __dir__(self):