diff --git a/data/telegram.org/js/telegram-webview.js b/data/telegram.org/js/telegram-webview.js
index e715b65c9f..a59bbf6229 100644
--- a/data/telegram.org/js/telegram-webview.js
+++ b/data/telegram.org/js/telegram-webview.js
@@ -599,6 +599,10 @@
       postEvent('web_app_close');
     }
   };
+  Object.defineProperty(window.Telegram.WebApp, 'viewportHeight', {
+    get: function(){ return (viewportHeight === false ? window.innerHeight : viewportHeight) - mainButtonHeight; },
+    enumerable: true
+  });
 
   if (webAppData.theme_params) {
     setThemeParams(webAppData.theme_params);
diff --git a/data/webappcontent.telegram.org/cafe.html b/data/webappcontent.telegram.org/cafe.html
index 82701c3685..ccbbcc0983 100644
--- a/data/webappcontent.telegram.org/cafe.html
+++ b/data/webappcontent.telegram.org/cafe.html
@@ -9,7 +9,7 @@
     <meta name="MobileOptimized" content="176" />
     <meta name="HandheldFriendly" content="True" />
     <meta name="robots" content="noindex, nofollow" />
-    <script src="https://tg.dev/js/telegram-webview.js?8"></script>
+    <script src="https://tg.dev/js/telegram-webview.js?9"></script>
     <script>
       function setThemeClass() {
         document.documentElement.className = document.documentElement.style.getPropertyValue('--tg-theme-color-scheme');
diff --git a/data/webappcontent.telegram.org/demo.html b/data/webappcontent.telegram.org/demo.html
index 68d083d1b3..8cd0def431 100644
--- a/data/webappcontent.telegram.org/demo.html
+++ b/data/webappcontent.telegram.org/demo.html
@@ -8,7 +8,7 @@
     <meta name="MobileOptimized" content="176" />
     <meta name="HandheldFriendly" content="True" />
     <meta name="robots" content="noindex,nofollow" />
-    <script src="https://telegram.org/js/telegram-webview.js?8"></script>
+    <script src="https://telegram.org/js/telegram-webview.js?9"></script>
     <script>
       function setThemeClass() {
         document.documentElement.className = document.documentElement.style.getPropertyValue('--tg-theme-color-scheme');