diff --git a/app/helpers/statistics_helper.rb b/app/helpers/statistics_helper.rb
index 2e2a7a23f..5e6dcd299 100644
--- a/app/helpers/statistics_helper.rb
+++ b/app/helpers/statistics_helper.rb
@@ -4,9 +4,9 @@ module StatisticsHelper
   def data_format_string num
     result = num
     if num < 1024 * 1024
-      result = format("%0.3f", (num/1024)) + " GB"
+      result = format("%0.3f", (num/1024)).to_s + " GB"
     else
-      result = format("%0.3f", (num/(1024*1024))) + " TB"
+      result = format("%0.3f", (num/(1024*1024))).to_s + " TB"
     end
   end
 end