diff --git a/nifty5/energies/kl.py b/nifty5/energies/kl.py
index 792ad8d4b7b6914541c3fbebf08a3eb43398041d..7cc988f0f1e7d3f1854a7b85e0b7f0f59b7ead71 100644
--- a/nifty5/energies/kl.py
+++ b/nifty5/energies/kl.py
@@ -1,6 +1,6 @@
 from builtins import *
 from ..minimization.energy import Energy
-from ..utilities import memo
+from ..utilities import memo, my_sum
 
 
 class SampledKullbachLeiblerDivergence(Energy):
diff --git a/nifty5/minimization/energy.py b/nifty5/minimization/energy.py
index 213466aa4df75c66c90ca4495a255f6587c30c10..0104bbbf69439b6932d38b03b93cc0dfc06755da 100644
--- a/nifty5/minimization/energy.py
+++ b/nifty5/minimization/energy.py
@@ -130,6 +130,7 @@ class Energy(NiftyMetaBase()):
         return None
 
     def makeInvertible(self, controller, preconditioner=None):
+        from .iteration_controller import IterationController
         if not isinstance(controller, IterationController):
             raise TypeError
         return CurvatureInversionEnabler(self, controller, preconditioner)