diff --git a/gnpy/topology/spectrum_assignment.py b/gnpy/topology/spectrum_assignment.py
index 664ab4fd..20ac2dba 100644
--- a/gnpy/topology/spectrum_assignment.py
+++ b/gnpy/topology/spectrum_assignment.py
@@ -15,7 +15,6 @@ element/oms correspondace
 
 from collections import namedtuple
 from logging import getLogger
-from math import ceil
 from gnpy.core.elements import Roadm, Transceiver
 from gnpy.core.exceptions import ServiceError, SpectrumError
 from gnpy.topology.request import compute_spectrum_slot_vs_bandwidth