diff --git a/lbmpy/methods/momentbased/momentbasedsimplifications.py b/lbmpy/methods/momentbased/momentbasedsimplifications.py
index c307b23dfc480620a96e74e22a619ef9b0c79fd0..40ec979f866880a92500804376253294e8263f58 100644
--- a/lbmpy/methods/momentbased/momentbasedsimplifications.py
+++ b/lbmpy/methods/momentbased/momentbasedsimplifications.py
@@ -43,7 +43,7 @@ def factor_relaxation_rates(cr: LbmCollisionRule):
     """
     sh = cr.simplification_hints
     assert 'relaxation_rates' in sh, "Needs simplification hint 'relaxation_rates': Sequence of relaxation rates"
-    if len(sh['relaxation_rates']) > 19:  # heuristics, works well if there is a small number of relaxation rates
+    if len(set(sh['relaxation_rates'])) > 19:  # heuristics, works well if there is a small number of relaxation rates
         return cr
 
     relaxation_rates = sp.Matrix(sh['relaxation_rates']).atoms(sp.Symbol)