diff --git a/docs/introduction.md b/docs/introduction.md
index 44059206..0f4abb30 100644
--- a/docs/introduction.md
+++ b/docs/introduction.md
@@ -24,7 +24,7 @@ def main(page: ft.Page):
     page.title = "Flet counter example"
     page.vertical_alignment = ft.MainAxisAlignment.CENTER
 
-    txt_number = ft.TextField(value="0", text_align=ft.TextAlign.RIGHT, width=100)
+    txt_number = ft.TextField(value="0", text_align=ft.TextAlign.RIGHT, width=100, input_filter=ft.NumbersOnlyInputFilter())
 
     def minus_click(e):
         txt_number.value = str(int(txt_number.value) - 1)