diff --git a/spec/robots/dor_repo/gis_assembly/generate_mods_spec.rb b/spec/robots/dor_repo/gis_assembly/generate_mods_spec.rb
index b582abbc..1607d262 100644
--- a/spec/robots/dor_repo/gis_assembly/generate_mods_spec.rb
+++ b/spec/robots/dor_repo/gis_assembly/generate_mods_spec.rb
@@ -29,7 +29,7 @@
 
     it 'runs without error' do
       expect do
-        subject.to_mods(geo_metadata, { purl: 'https://purl.stanford.edu/ym947vs2726', newfoo: 123 })
+        subject.to_mods(geo_metadata, { purl: 'https://purl.stanford.edu/ym947vs2726', newfoo: '123' })
       end.not_to raise_error
     end
   end