Fix typo.
diff --git a/Doc/library/email.headerregistry.rst b/Doc/library/email.headerregistry.rst
index 2e9224a..af72b7c 100644
--- a/Doc/library/email.headerregistry.rst
+++ b/Doc/library/email.headerregistry.rst
@@ -268,7 +268,7 @@
     also take a list of supplemental parameters, which have a common format.
     This class serves as a base for all the MIME headers that take parameters.
 
-    .. attrbibute:: params
+    .. attribute:: params
 
        A dictionary mapping parameter names to parameter values.