diff --git a/app/models/concerns/importable.rb b/app/models/concerns/importable.rb
index d0f1c53..b4da63b 100644
--- a/app/models/concerns/importable.rb
+++ b/app/models/concerns/importable.rb
@@ -42,7 +42,10 @@ def validate_prefix(doi)
     end
 
     def normalize_doi(doi)
+      Rails.logger.info("[Event Import Worker: normalize doi]")
+      Rails.logger.info("[Event Import Worker: normalize doi -> doi = #{doi}]")
       doi = validate_doi(doi)
+      Rails.logger.info("[Event Import Worker: normalize doi (After validation) -> doi = #{doi}]")
       return nil if doi.blank?
 
       # remove non-printing whitespace and downcase