diff --git a/dom/base/Document.cpp b/dom/base/Document.cpp
index 3330ba5ccf98..7000333b3db4 100644
--- a/dom/base/Document.cpp
+++ b/dom/base/Document.cpp
@@ -11155,6 +11155,8 @@ void Document::DocAddSizeOfExcludingThis(nsWindowSizes& aWindowSizes) const {
     mPresShell->AddSizeOfIncludingThis(aWindowSizes);
   }
 
+  mStyleSet->AddSizeOfIncludingThis(aWindowSizes);
+
   aWindowSizes.mDOMOtherSize += mLangGroupFontPrefs.SizeOfExcludingThis(
       aWindowSizes.mState.mMallocSizeOf);
 
diff --git a/layout/base/PresShell.cpp b/layout/base/PresShell.cpp
index 3f1beee6190f..72b8d87a2385 100644
--- a/layout/base/PresShell.cpp
+++ b/layout/base/PresShell.cpp
@@ -10559,8 +10559,6 @@ void PresShell::AddSizeOfIncludingThis(nsWindowSizes& aSizes) const {
       mPendingScrollAnchorSelection.ShallowSizeOfExcludingThis(mallocSizeOf) +
       mPendingScrollAnchorAdjustment.ShallowSizeOfExcludingThis(mallocSizeOf);
 
-  StyleSet()->AddSizeOfIncludingThis(aSizes);
-
   aSizes.mLayoutTextRunsSize += SizeOfTextRuns(mallocSizeOf);
 
   aSizes.mLayoutPresContextSize +=