diff --git a/binarycpython/utils/grid.py b/binarycpython/utils/grid.py
index 11aae04939b1ef7d9118f30dc82307fda444cf46..785ddf13a07d720f20880d58a7e34e334769983b 100644
--- a/binarycpython/utils/grid.py
+++ b/binarycpython/utils/grid.py
@@ -4258,7 +4258,7 @@ class Population:
             precode='self.grid_options["multiplicity"] = multiplicity; self.bse_options["multiplicity"] = multiplicity; options={}'.format(
                 self.grid_options["Moe2017_options"]
             ),
-            condition="({}[multiplicity-1] > 0)".format(
+            condition="({}[int(multiplicity)-1] > 0)".format(
                 str(self.grid_options["Moe2017_options"]["multiplicity_modulator"])
             ),
             gridtype="edge",