diff --git a/nifty/operators/linear_operator/linear_operator.py b/nifty/operators/linear_operator/linear_operator.py
index c57e03972f33cb6f46ade9abddb704c0a1878727..38b52f341861758597c664fc917a39b4d67493b8 100644
--- a/nifty/operators/linear_operator/linear_operator.py
+++ b/nifty/operators/linear_operator/linear_operator.py
@@ -73,7 +73,7 @@ class LinearOperator(Loggable, object):
     __metaclass__ = NiftyMeta
 
     def __init__(self, default_spaces=None):
-        self.default_spaces = default_spaces
+        self._default_spaces = default_spaces
 
     @staticmethod
     def _parse_domain(domain):
@@ -119,10 +119,6 @@ class LinearOperator(Loggable, object):
     def default_spaces(self):
         return self._default_spaces
 
-    @default_spaces.setter
-    def default_spaces(self, spaces):
-        self._default_spaces = utilities.cast_axis_to_tuple(spaces)
-
     def __call__(self, *args, **kwargs):
         return self.times(*args, **kwargs)
 
diff --git a/nifty/operators/smoothing_operator/smoothing_operator.py b/nifty/operators/smoothing_operator/smoothing_operator.py
index b306b8c2d3b1f1274d0a35c42406614694335e36..63843630e5aca298093263d4716ebcd538167624 100644
--- a/nifty/operators/smoothing_operator/smoothing_operator.py
+++ b/nifty/operators/smoothing_operator/smoothing_operator.py
@@ -135,8 +135,8 @@ class SmoothingOperator(EndomorphicOperator):
         #                      "space as input domain.")
         self._domain = self._parse_domain(domain)
 
-        self.sigma = sigma
-        self.log_distances = log_distances
+        self._sigma = sigma
+        self._log_distances = log_distances
 
     def _inverse_times(self, x, spaces):
         if self.sigma == 0:
@@ -183,18 +183,10 @@ class SmoothingOperator(EndomorphicOperator):
     def sigma(self):
         return self._sigma
 
-    @sigma.setter
-    def sigma(self, sigma):
-        self._sigma = np.float(sigma)
-
     @property
     def log_distances(self):
         return self._log_distances
 
-    @log_distances.setter
-    def log_distances(self, log_distances):
-        self._log_distances = bool(log_distances)
-
     @abc.abstractmethod
     def _smooth(self, x, spaces, inverse):
         raise NotImplementedError