diff --git a/nifty5/operators/sum_operator.py b/nifty5/operators/sum_operator.py
index bdda12263f97f8617c8a89f2f3be4fb74b1b8a7b..9daf7311c32143be78976b5e6a0cdad2726ec3e7 100644
--- a/nifty5/operators/sum_operator.py
+++ b/nifty5/operators/sum_operator.py
@@ -193,6 +193,9 @@ class SumOperator(LinearOperator):
                 "cannot draw from inverse of this operator")
         res = None
         for op in self._ops:
+            from .simple_linear_operators import NullOperator
+            if isinstance(op, NullOperator):
+                continue
             tmp = op.draw_sample(from_inverse, dtype)
             res = tmp if res is None else res.unite(tmp)
         return res