diff --git a/mechanicalsoup/form.py b/mechanicalsoup/form.py
index 2820b592..26136623 100644
--- a/mechanicalsoup/form.py
+++ b/mechanicalsoup/form.py
@@ -263,7 +263,7 @@ def set(self, name, value, force=False):
 
         .. code-block:: python
 
-            form.set("tagname") = path_to_local_file
+            form.set("tagname", path_to_local_file)
 
         """
         for func in ("checkbox", "radio", "input", "textarea", "select"):