diff --git a/src/Ubiety.Stringprep.Core/ProhibitedValueStep.cs b/src/Ubiety.Stringprep.Core/ProhibitedValueStep.cs
index 7d29e74..f0d7c86 100644
--- a/src/Ubiety.Stringprep.Core/ProhibitedValueStep.cs
+++ b/src/Ubiety.Stringprep.Core/ProhibitedValueStep.cs
@@ -49,10 +49,10 @@ public string Run(string input)
             var item = input.Where(value => table.Contains(value)).FirstOrDefault();
             if (item != null)
             {
-                throw new ProhibitedValueException(value);
+                throw new ProhibitedValueException(item);
             }
 
             return input;
         }
     }
-}
+}
\ No newline at end of file