diff --git a/nifty/energies/line_energy.py b/nifty/energies/line_energy.py
index 0271f6dbc9e3c4e2e76516e91b7a6d9789a1fd82..1deb6fd9de808d57b3f4fec78a62b736e393cd63 100644
--- a/nifty/energies/line_energy.py
+++ b/nifty/energies/line_energy.py
@@ -17,7 +17,7 @@
 # and financially supported by the Studienstiftung des deutschen Volkes.
 
 
-class LineEnergy:
+class LineEnergy(object):
     """ Evaluates an underlying Energy along a certain line direction.
 
     Given an Energy class and a line direction, its position is parametrized by