diff --git a/datasources/transforms/derivated_tag.rb b/datasources/transforms/derivated_tag.rb
index 5e8d3b9..824a383 100755
--- a/datasources/transforms/derivated_tag.rb
+++ b/datasources/transforms/derivated_tag.rb
@@ -25,6 +25,7 @@ def initialize(settings)
   end
 
   def process_data(row)
+    row[:properties][@property] ||= {}
     row[:properties][@property][@key] = @lambda_value.call(row[:properties])
     row
   end