diff --git a/lib/ncbo_annotator.rb b/lib/ncbo_annotator.rb
index 3fbbae28..5f69c43f 100644
--- a/lib/ncbo_annotator.rb
+++ b/lib/ncbo_annotator.rb
@@ -339,7 +339,7 @@ def create_term_cache_for_submission(logger, sub, redis=nil, redis_prefix=nil)
                                     resourceId,
                                     Annotator::Annotation::MATCH_TYPES[:type_synonym],
                                     syn,
-                                    semanticTypes) unless (syn.casecmp(prefLabel) == 0)
+                                    semanticTypes) unless (syn.to_s.casecmp(prefLabel) == 0)
                 end
                 create_term_entry(redis,
                                   redis_prefix,
@@ -661,11 +661,11 @@ def redis_last_mgrep_restart_default_timestamp()
       def create_term_entry(redis, instance_prefix, ontResourceId, resourceId, label_type, val, semanticTypes)
         begin
           # NCBO-696 - Remove case-sensitive variations on terms in annotator dictionary
-          val.upcase!()
+          val.to_s.upcase!()
         rescue ArgumentError => e
           # NCBO-832 - SCTSPA Annotator Cache building error (UTF-8)
           val = val.encode('UTF-8', 'binary', invalid: :replace, undef: :replace, replace: '')
-          val.upcase!()
+          val.to_s.upcase!()
         end
 
         # exclude single-character or empty/null values