new file mode 100644
--- /dev/null
+++ b/layout/reftests/svg/mask-root-svg.svg
@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" version="1.0" mask="url(#mask1)">
+  <defs>
+    <mask id="mask1" maskUnits="objectBoundingBox" maskContentUnits="objectBoundingBox" x="0" y="0" width="0.5" height="0.5">
+      <rect x="0" y="0" width="1" height="1" style="stroke:none; fill: #ffffff"/>
+    </mask>
+  </defs>
+  <rect width="50%" height="50%" fill="white"/>
+  <rect x="30%" y="30%" width="20%" height="20%" fill="lime"/>
+</svg>

--- a/layout/reftests/svg/reftest.list
+++ b/layout/reftests/svg/reftest.list
@@ -273,16 +273,17 @@ fuzzy-if(skiaContent,1,10000) == mask-ba
 == mask-contains-inner-svg-01.svg pass.svg
 == mask-contains-inner-svg-02.svg pass.svg
 == mask-empty-size.svg about:blank
 == mask-extref-dataURI-01.svg pass.svg
 == mask-img.html mask-img-ref.html
 == mask-on-outflowElement-01a.html clipPath-on-outflowElement-01-ref.html
 == mask-on-outflowElement-01b.html clipPath-on-outflowElement-01-ref.html
 fuzzy(1,5000) == mask-opacity-01.svg mask-opacity-01-ref.svg
+!= mask-root-svg.svg about:blank
 == mask-transformed-01.svg mask-transformed-01-ref.svg
 == mask-transformed-02.svg pass.svg
 == mask-transformed-child-01.svg mask-transformed-child-01-ref.svg
 # fuzzy because of the differences between clipPath and mask clipping
 fuzzy-if(d2d||skiaContent,1,6400) == mask-type-01.svg mask-type-01-ref.svg
 fuzzy-if(d2d||skiaContent,1,6400) == mask-type-02.svg mask-type-01-ref.svg
 fuzzy-if(d2d||skiaContent,1,6400) == mask-type-03.svg mask-type-01-ref.svg
 fuzzy-if(d2d||skiaContent,1,6400) == mask-type-04.svg mask-type-01-ref.svg