diff --git a/README.rst b/README.rst
index acace52..2c43f99 100644
--- a/README.rst
+++ b/README.rst
@@ -98,6 +98,8 @@ Parameters of the **`simplify\_mesh\_lossless`** method that can be tuned.
     Maximal error after which a vertex is not deleted.
 -  **max\_iterations**
     Maximum number of iterations.
+-  **preserve\_border**
+    Flag for preserving the vertices situated on open borders. *needs more validation*
 
 Note
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