diff --git a/mozilla/layout/reftests/bugs/345563-sub.xhtml b/mozilla/layout/reftests/bugs/345563-sub.xhtml
new file mode 100644
index 00000000000..0d777528b95
--- /dev/null
+++ b/mozilla/layout/reftests/bugs/345563-sub.xhtml
@@ -0,0 +1,22 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/xhtml-math11-f.dtd" >
+
+<html xmlns="http://www.w3.org/1999/xhtml">
+
+<head>
+
+</head>
+
+<body>
+
+<p>
+  <math xmlns="http://www.w3.org/1998/Math/MathML">
+    <msub>
+      <mi>x</mi>
+      <mn>2</mn>
+    </msub>
+  </math>
+</p>
+
+</body>
+
+</html>
diff --git a/mozilla/layout/reftests/bugs/345563-sup.xhtml b/mozilla/layout/reftests/bugs/345563-sup.xhtml
new file mode 100644
index 00000000000..dc57aa35066
--- /dev/null
+++ b/mozilla/layout/reftests/bugs/345563-sup.xhtml
@@ -0,0 +1,22 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN" "http://www.w3.org/Math/DTD/mathml2/xhtml-math11-f.dtd" >
+
+<html xmlns="http://www.w3.org/1999/xhtml">
+
+<head>
+
+</head>
+
+<body>
+
+<p>
+  <math xmlns="http://www.w3.org/1998/Math/MathML">
+    <msup>
+      <mi>x</mi>
+      <mn>2</mn>
+    </msup>
+  </math>
+</p>
+
+</body>
+
+</html>
diff --git a/mozilla/layout/reftests/bugs/reftest.list b/mozilla/layout/reftests/bugs/reftest.list
index 55d92ecc07d..27950a3c1c5 100644
--- a/mozilla/layout/reftests/bugs/reftest.list
+++ b/mozilla/layout/reftests/bugs/reftest.list
@@ -299,6 +299,7 @@ random-if(MOZ_WIDGET_TOOLKIT=="gtk2") == 333970-1.html 333970-1-ref.html # bug 3
 == 345267-1b.html 345267-1-ref.html
 == 345267-1c.html 345267-1-ref.html
 == 345267-1d.html 345267-1-ref.html
+!= 345563-sub.xhtml 345563-sup.xhtml 
 == 346774-1a.html 346774-1-ref.html
 == 346774-1b.html 346774-1-ref.html
 == 346774-1c.html 346774-1-ref.html
