diff --git a/Requirements.md b/Requirements.md
index a4b6988..6b18261 100644
--- a/Requirements.md
+++ b/Requirements.md
@@ -2,5 +2,6 @@
 
   - PHP 5.6 (or higher)
   - `openssl` extension
+  - `libxml` extension
 
 Turn on the OpenSSL support by un-commenting the line `extension=php_openssl.dll` in your PHP configuration (`php.ini`)
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