--- a/layout/style/ServoStyleSheet.cpp
+++ b/layout/style/ServoStyleSheet.cpp
@@ -171,17 +171,22 @@ ServoStyleSheet::ParseSheet(css::Loader*
 
   Inner()->mURLData = extraData.forget();
   return NS_OK;
 }
 
 void
 ServoStyleSheet::LoadFailed()
 {
-  Inner()->mSheet = Servo_StyleSheet_Empty(mParsingMode).Consume();
+  if (!Inner()->mSheet) {
+    // Only create empty stylesheet if this is a top level stylesheet.
+    // The raw sheet for stylesheet of @import rule is already set in
+    // loader, and we should not touch it.
+    Inner()->mSheet = Servo_StyleSheet_Empty(mParsingMode).Consume();
+  }
   Inner()->mURLData = URLExtraData::Dummy();
 }
 
 nsresult
 ServoStyleSheet::ReparseSheet(const nsAString& aInput)
 {
   // TODO(kuoe0): Bug 1367996 - Need to call document notification
   // (StyleRuleAdded() and StyleRuleRemoved()) like what we do in