1 files changed, 1 insertions, 1 deletions
diff --git a/core/fpdfapi/page/cpdf_contentmark.h b/core/fpdfapi/page/cpdf_contentmark.h
index dc4cc08838..1395db12f8 100644
--- a/core/fpdfapi/page/cpdf_contentmark.h
+++ b/core/fpdfapi/page/cpdf_contentmark.h
@@ -40,7 +40,7 @@ class CPDF_ContentMark {
   size_t FindFirstDifference(const CPDF_ContentMark* other) const;
 
  private:
-  class MarkData : public Retainable {
+  class MarkData final : public Retainable {
    public:
     MarkData();
     MarkData(const MarkData& src);