diff --git a/layout/mathml/nsMathMLmunderoverFrame.cpp b/layout/mathml/nsMathMLmunderoverFrame.cpp
index 60bab2205d25..dc2c36796e95 100644
--- a/layout/mathml/nsMathMLmunderoverFrame.cpp
+++ b/layout/mathml/nsMathMLmunderoverFrame.cpp
@@ -419,7 +419,8 @@ nsMathMLmunderoverFrame::Place(nsRenderingContext& aRenderingContext,
 
   mBoundingMetrics.ascent = 
     bmBase.ascent + overDelta1 + bmOver.ascent + bmOver.descent;
-  mBoundingMetrics.descent = bmBase.descent;
+  mBoundingMetrics.descent = 
+    bmBase.descent + underDelta1 + bmUnder.ascent + bmUnder.descent;
   mBoundingMetrics.leftBearing = 
     NS_MIN(dxBase + bmBase.leftBearing, dxOver + bmOver.leftBearing);
   mBoundingMetrics.rightBearing = 
@@ -462,9 +463,6 @@ nsMathMLmunderoverFrame::Place(nsRenderingContext& aRenderingContext,
 
   mBoundingMetrics.width =
     NS_MAX(dxAnonymousBase + bmAnonymousBase.width, dxUnder + bmUnder.width);
-  // At this point, mBoundingMetrics.ascent = bmAnonymousBase.ascent 
-  mBoundingMetrics.descent = 
-    bmAnonymousBase.descent + underDelta1 + bmUnder.ascent + bmUnder.descent;
   mBoundingMetrics.leftBearing =
     NS_MIN(dxAnonymousBase + bmAnonymousBase.leftBearing, dxUnder + bmUnder.leftBearing);
   mBoundingMetrics.rightBearing =