--- a/layout/mathml/base/src/nsMathMLmrootFrame.cpp
+++ b/layout/mathml/base/src/nsMathMLmrootFrame.cpp
@@ -410,17 +410,17 @@ nsMathMLmrootFrame::GetIntrinsicWidth(ns
                                          nsLayoutUtils::PREF_WIDTH);
   nscoord sqrWidth = mSqrChar.GetMaxWidth(PresContext(), *aRenderingContext);
 
   nsCOMPtr<nsIFontMetrics> fm;
   aRenderingContext->GetFontMetrics(*getter_AddRefs(fm));
   nscoord dxSqr;
   GetRadicalXOffsets(indexWidth, sqrWidth, fm, nsnull, &dxSqr);
 
-  return dxSqr + baseWidth;
+  return dxSqr + sqrWidth + baseWidth;
 }
 
 // ----------------------
 // the Style System will use these to pass the proper style context to our MathMLChar
 nsStyleContext*
 nsMathMLmrootFrame::GetAdditionalStyleContext(PRInt32 aIndex) const
 {
   switch (aIndex) {