diff --git a/html5lib/filters/sanitizer.py b/html5lib/filters/sanitizer.py
index dc801668..fd35c85c 100644
--- a/html5lib/filters/sanitizer.py
+++ b/html5lib/filters/sanitizer.py
@@ -111,6 +111,8 @@
     (namespaces['html'], 'ul'),
     (namespaces['html'], 'var'),
     (namespaces['html'], 'video'),
+    (namespaces['mathml'], 'annotation'),
+    (namespaces['mathml'], 'annotation-xml'),
     (namespaces['mathml'], 'maction'),
     (namespaces['mathml'], 'math'),
     (namespaces['mathml'], 'merror'),
@@ -138,6 +140,7 @@
     (namespaces['mathml'], 'munder'),
     (namespaces['mathml'], 'munderover'),
     (namespaces['mathml'], 'none'),
+    (namespaces['mathml'], 'semantics'),
     (namespaces['svg'], 'a'),
     (namespaces['svg'], 'animate'),
     (namespaces['svg'], 'animateColor'),