--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -76,18 +76,19 @@ ServoStyleSet::Init(nsPresContext* aPres
       // type, which this preserves.
 
       MOZ_ASSERT(sheet->RawContents(),
                  "We should only append non-null raw sheets.");
       Servo_StyleSet_AppendStyleSheet(mRawSet.get(), sheet);
     }
   }
 
-  // No need to Servo_StyleSet_FlushStyleSheets because we just created the
-  // mRawSet, so there was nothing to flush.
+  // We added prefilled stylesheets into mRawSet, so the stylist is dirty.
+  // The Stylist should be updated later when necessary.
+  SetStylistStyleSheetsDirty();
 }
 
 void
 ServoStyleSet::BeginShutdown()
 {
   nsIDocument* doc = mPresContext->Document();
 
   // Remove the style rule map from document's observer and drop it.