diff --git a/lib/utility.lua b/lib/utility.lua
index d9c0ac0..fb9d28a 100644
--- a/lib/utility.lua
+++ b/lib/utility.lua
@@ -552,7 +552,7 @@ end
 utility.mean = function(object)
   local total, count = 0, 0
   for _, value in pairs(object) do
-    total = total = value
+    total = total + value
     count = count + 1
   end
   return total / count, total, count