diff --git a/Elwig/Helpers/Validator.cs b/Elwig/Helpers/Validator.cs
index 4b402e7..9a88049 100644
--- a/Elwig/Helpers/Validator.cs
+++ b/Elwig/Helpers/Validator.cs
@@ -302,7 +302,7 @@ namespace Elwig.Helpers {
 
                 // http://www.pruefziffernberechnung.de/U/USt-IdNr.shtml
                 int s = 0, v = 0;
-                for (int i = 0; i < 8; i++)
+                for (int i = 0; i < 7; i++)
                     s += ((text[i + 3] - '0') * (i % 2 + 1)).ToString().Select(ch => ch - '0').Sum();
                 v = (96 - s) % 10;