diff --git a/lib/diaspora_federation.rb b/lib/diaspora_federation.rb
index b3edaa5..85ba255 100644
--- a/lib/diaspora_federation.rb
+++ b/lib/diaspora_federation.rb
@@ -89,7 +89,7 @@ module DiasporaFederation
     attr_accessor :person_class
 
     def person_class=(klass)
-      @person_class = klass.to_s
+      @person_class = klass.nil? ? nil : klass.to_s
     end
 
     def person_class
diff --git a/spec/lib/diaspora_federation_spec.rb b/spec/lib/diaspora_federation_spec.rb
index 1bb17aa..d81c0ec 100644
--- a/spec/lib/diaspora_federation_spec.rb
+++ b/spec/lib/diaspora_federation_spec.rb
@@ -17,7 +17,7 @@ module DiasporaFederation
         temp = DiasporaFederation.person_class
         DiasporaFederation.person_class = nil
         expect { DiasporaFederation.validate_config }.to raise_error ConfigurationError
-        DiasporaFederation.person_class = temp.to_s
+        DiasporaFederation.person_class = temp
       end
     end
   end