diff --git a/openmc/tallies.py b/openmc/tallies.py
index 646482ede9..048bd99513 100644
--- a/openmc/tallies.py
+++ b/openmc/tallies.py
@@ -354,7 +354,7 @@ class Tally(IDManagerMixin):
             if nuc in visited_nuclides:
                 msg = 'Unable to add a duplicate nuclide "{}" to Tally ID="{}" ' \
                       'since duplicate nuclides are not supported in the OpenMC ' \
-                      'Python API'.format(nuclide, self.id)
+                      'Python API'.format(nuc, self.id)
                 raise ValueError(msg)
             visited_nuclides.add(nuc)