diff --git a/aplK.py b/aplK.py
index aaee689..afddda7 100644
--- a/aplK.py
+++ b/aplK.py
@@ -1141,7 +1141,7 @@ class AlgebraAplK(UniqueRepresentation, Parent):
             for k in self.elements.keys():
                 dim = len(k)-1
                 # the sign is due to stoke's theorem
-                cochain[k] = ((-1) ** (((dim) * (dim-1)) // 2)) * \
+                cochain[k] = ((-1) ** ((dim*(dim-1)) // 2)) * \
                     self.elements[k].integral()
             return cochain