diff --git a/plugins/discourse-narrative-bot/lib/discourse_narrative_bot/certificate_generator.rb b/plugins/discourse-narrative-bot/lib/discourse_narrative_bot/certificate_generator.rb
index 5e25bb851f0..411cf1c8a27 100644
--- a/plugins/discourse-narrative-bot/lib/discourse_narrative_bot/certificate_generator.rb
+++ b/plugins/discourse-narrative-bot/lib/discourse_narrative_bot/certificate_generator.rb
@@ -80,6 +80,7 @@ module DiscourseNarrativeBot
     end
 
     def base64_image_data(data)
+      return "" if data.blank?
       "xlink:href=\"data:image/png;base64,#{Base64.strict_encode64(data)}\""
     end