--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -1031,16 +1031,20 @@ ServoStyleSet::StyleNewSubtree(Element* 
                             ServoTraversalFlags::ClearAnimationOnlyDirtyDescendants);
     MOZ_ASSERT(!postTraversalRequired);
   }
 }
 
 void
 ServoStyleSet::MarkOriginsDirty(OriginFlags aChangedOrigins)
 {
+  if (MOZ_UNLIKELY(!mRawSet)) {
+    return;
+  }
+
   SetStylistStyleSheetsDirty();
   Servo_StyleSet_NoteStyleSheetsChanged(mRawSet.get(),
                                         mAuthorStyleDisabled,
                                         aChangedOrigins);
 }
 
 void
 ServoStyleSet::SetStylistStyleSheetsDirty()