diff --git a/NHSE.WinForms/Subforms/Map/MapDumpHelper.cs b/NHSE.WinForms/Subforms/Map/MapDumpHelper.cs
index 85ca084..82f851e 100644
--- a/NHSE.WinForms/Subforms/Map/MapDumpHelper.cs
+++ b/NHSE.WinForms/Subforms/Map/MapDumpHelper.cs
@@ -245,8 +245,8 @@ public static bool ImportMapAcresAll(byte[] data)
                 return false;
             }
 
-            modified.CopyTo(data, modified.Length);
+            modified.CopyTo(data, 0);
             return true;
         }
     }
-}
\ No newline at end of file
+}