diff --git a/lib/importer/paper.rb b/lib/importer/paper.rb
index fa0f470..b7e6721 100644
--- a/lib/importer/paper.rb
+++ b/lib/importer/paper.rb
@@ -27,7 +27,7 @@ def self.get_by_doi(result)
     end
 
     def self.doi_url(doi)
-      "http://dx.doi.org/" + doi
+      "https://doi.org/" + doi
     end
 
     def initialize(result, text, source)