diff --git a/fpdfsdk/fpdf_editpage.cpp b/fpdfsdk/fpdf_editpage.cpp
index 02c07d1..dbf9124 100644
--- a/fpdfsdk/fpdf_editpage.cpp
+++ b/fpdfsdk/fpdf_editpage.cpp
@@ -306,13 +306,16 @@
 
 FPDF_EXPORT FPDF_PAGEOBJECTMARK FPDF_CALLCONV
 FPDFPageObj_AddMark(FPDF_PAGEOBJECT page_object, FPDF_BYTESTRING name) {
-  if (!page_object)
+  CPDF_PageObject* pPageObj = CPDFPageObjectFromFPDFPageObject(page_object);
+  if (!pPageObj)
     return nullptr;
 
-  auto* mark = &CPDFPageObjectFromFPDFPageObject(page_object)->m_ContentMark;
+  auto* mark = &pPageObj->m_ContentMark;
   mark->AddMark(name);
   unsigned long index = mark->CountItems() - 1;
 
+  pPageObj->SetDirty(true);
+
   return FPDFPageObjectMarkFromCPDFContentMarkItem(mark->GetItem(index));
 }