diff --git a/mozilla/layout/reftests/mathml/non-spacing-accent-1-ref.xhtml b/mozilla/layout/reftests/mathml/non-spacing-accent-1-ref.xhtml
new file mode 100644
index 00000000000..9c5a9145f86
--- /dev/null
+++ b/mozilla/layout/reftests/mathml/non-spacing-accent-1-ref.xhtml
@@ -0,0 +1,17 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <style type="text/css">
+      html { background-color: white }
+      mi { color: white; }
+      mo { color: red; }
+    </style>
+  </head>
+<body>
+  <math xmlns="http://www.w3.org/1998/Math/MathML">
+    <mover>
+      <mi>a</mi>
+      <mo>&#x302;</mo>
+    </mover>
+  </math>
+</body>
+</html>
diff --git a/mozilla/layout/reftests/mathml/non-spacing-accent-1.xhtml b/mozilla/layout/reftests/mathml/non-spacing-accent-1.xhtml
new file mode 100644
index 00000000000..b9133ddd165
--- /dev/null
+++ b/mozilla/layout/reftests/mathml/non-spacing-accent-1.xhtml
@@ -0,0 +1,18 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <title>Check that non-spacing marks in accents are visible</title>
+    <style type="text/css">
+      html { background-color: white }
+      mi { color: white; }
+      mo { color: black; }
+    </style>
+  </head>
+<body>
+  <math xmlns="http://www.w3.org/1998/Math/MathML">
+    <mover>
+      <mi>a</mi>
+      <mo>&#x302;</mo>
+    </mover>
+  </math>
+</body>
+</html>
diff --git a/mozilla/layout/reftests/mathml/reftest.list b/mozilla/layout/reftests/mathml/reftest.list
index 18c8a1333b5..a8643e778b7 100644
--- a/mozilla/layout/reftests/mathml/reftest.list
+++ b/mozilla/layout/reftests/mathml/reftest.list
@@ -1,3 +1,4 @@
 == mi-mathvariant-1.xhtml mi-mathvariant-1-ref.xhtml
 == mi-mathvariant-2.xhtml mi-mathvariant-2-ref.xhtml
 == table-width-1.xhtml table-width-1-ref.xhtml
+!= non-spacing-accent-1.xhtml non-spacing-accent-1-ref.xhtml
