diff --git a/lib/submitters/submit_values.rb b/lib/submitters/submit_values.rb
index 4e330b54..65ecad75 100644
--- a/lib/submitters/submit_values.rb
+++ b/lib/submitters/submit_values.rb
@@ -93,7 +93,11 @@ module Submitters
         if params[:cast_boolean] == 'true'
           v == 'true'
         elsif params[:cast_number] == 'true'
-          (v.to_f % 1).zero? ? v.to_i : v.to_f
+          if v == ''
+            nil
+          else
+            (v.to_f % 1).zero? ? v.to_i : v.to_f
+          end
         elsif params[:normalize_phone] == 'true'
           v.to_s.gsub(/[^0-9+]/, '')
         else