diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 2ce880b..3012690 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -15,6 +15,7 @@
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_linearized_header.h"
 #include "core/fpdfapi/parser/cpdf_name.h"
+#include "core/fpdfapi/parser/cpdf_null.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fpdfapi/parser/cpdf_parser.h"
 #include "core/fpdfapi/parser/cpdf_read_validator.h"
@@ -587,20 +588,54 @@
   return m_pParser ? m_pParser->GetIDArray() : nullptr;
 }
 
-void CPDF_Document::DeletePage(int iPage) {
+uint32_t CPDF_Document::DeletePage(int iPage) {
   RetainPtr<CPDF_Dictionary> pPages = GetMutablePagesDict();
-  if (!pPages)
-    return;
+  if (!pPages) {
+    return 0;
+  }
 
   int nPages = pPages->GetIntegerFor("Count");
-  if (iPage < 0 || iPage >= nPages)
-    return;
+  if (iPage < 0 || iPage >= nPages) {
+    return 0;
+  }
+
+  RetainPtr<const CPDF_Dictionary> page_dict = GetPageDictionary(iPage);
+  if (!page_dict) {
+    return 0;
+  }
 
   std::set<RetainPtr<CPDF_Dictionary>> stack = {pPages};
-  if (!InsertDeletePDFPage(std::move(pPages), iPage, nullptr, false, &stack))
-    return;
+  if (!InsertDeletePDFPage(std::move(pPages), iPage, nullptr, false, &stack)) {
+    return 0;
+  }
 
   m_PageList.erase(m_PageList.begin() + iPage);
+  return page_dict->GetObjNum();
+}
+
+void CPDF_Document::SetPageToNullObject(uint32_t page_obj_num) {
+  if (!page_obj_num || m_PageList.empty()) {
+    return;
+  }
+
+  // Load all pages so `m_PageList` has all the object numbers.
+  for (size_t i = 0; i < m_PageList.size(); ++i) {
+    GetPageDictionary(i);
+  }
+
+  if (pdfium::Contains(m_PageList, page_obj_num)) {
+    return;
+  }
+
+  // If `page_dict` is no longer in the page tree, replace it with an object of
+  // type null.
+  //
+  // Delete the object first from this container, so the conditional in the
+  // replacement call always evaluates to true.
+  DeleteIndirectObject(page_obj_num);
+  const bool replaced = ReplaceIndirectObjectIfHigherGeneration(
+      page_obj_num, pdfium::MakeRetain<CPDF_Null>());
+  CHECK(replaced);
 }
 
 void CPDF_Document::SetRootForTesting(RetainPtr<CPDF_Dictionary> root) {
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 4e00e51..ac162a6 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -33,7 +33,7 @@
    public:
     virtual ~Extension() = default;
     virtual int GetPageCount() const = 0;
-    virtual void DeletePage(int page_index) = 0;
+    virtual uint32_t DeletePage(int page_index) = 0;
     virtual bool ContainsExtensionForm() const = 0;
     virtual bool ContainsExtensionFullForm() const = 0;
     virtual bool ContainsExtensionForegroundForm() const = 0;
@@ -99,7 +99,12 @@
   RetainPtr<CPDF_Dictionary> GetInfo();
   RetainPtr<const CPDF_Array> GetFileIdentifier() const;
 
-  void DeletePage(int iPage);
+  // Returns the object number for the deleted page, or 0 on failure.
+  uint32_t DeletePage(int iPage);
+  // `page_obj_num` is the return value from DeletePage(). If it is non-zero,
+  // and it is no longer used in the page tree, then replace the page object
+  // with a null object.
+  void SetPageToNullObject(uint32_t page_obj_num);
   bool MovePages(pdfium::span<const int> page_indices, int dest_page_index);
 
   int GetPageCount() const;
diff --git a/fpdfsdk/fpdf_doc_embeddertest.cpp b/fpdfsdk/fpdf_doc_embeddertest.cpp
index 3cde698..8c44346 100644
--- a/fpdfsdk/fpdf_doc_embeddertest.cpp
+++ b/fpdfsdk/fpdf_doc_embeddertest.cpp
@@ -747,9 +747,8 @@
   EXPECT_EQ(1, FPDF_GetPageCount(document()));
 
   ASSERT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
-  // TODO(crbug.com/pdfium/2146): These should be 1.
-  EXPECT_EQ(2, CountPageEntries(GetString()));
-  EXPECT_EQ(2, CountStreamEntries(GetString()));
+  EXPECT_EQ(1, CountPageEntries(GetString()));
+  EXPECT_EQ(1, CountStreamEntries(GetString()));
 }
 
 TEST_F(FPDFDocEmbedderTest, DeletePageAndSaveWithCustomObject) {
@@ -761,8 +760,7 @@
   EXPECT_EQ(1, FPDF_GetPageCount(document()));
 
   ASSERT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
-  // TODO(crbug.com/pdfium/2146): This should be 1.
-  EXPECT_EQ(2, CountPageEntries(GetString()));
+  EXPECT_EQ(1, CountPageEntries(GetString()));
   EXPECT_EQ(1, CountStreamEntries(GetString()));
 }
 
@@ -793,8 +791,7 @@
   EXPECT_EQ(1, FPDF_GetPageCount(document()));
 
   ASSERT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
-  // TODO(crbug.com/pdfium/2146): This should be 1.
-  EXPECT_EQ(2, CountPageEntries(GetString()));
+  EXPECT_EQ(1, CountPageEntries(GetString()));
   EXPECT_EQ(1, CountStreamEntries(GetString()));
 }
 
diff --git a/fpdfsdk/fpdf_editpage.cpp b/fpdfsdk/fpdf_editpage.cpp
index e5c380a..ffc6a11 100644
--- a/fpdfsdk/fpdf_editpage.cpp
+++ b/fpdfsdk/fpdf_editpage.cpp
@@ -187,12 +187,9 @@
     return;
 
   CPDF_Document::Extension* pExtension = pDoc->GetExtension();
-  if (pExtension) {
-    pExtension->DeletePage(page_index);
-    return;
-  }
-
-  pDoc->DeletePage(page_index);
+  const uint32_t page_obj_num = pExtension ? pExtension->DeletePage(page_index)
+                                           : pDoc->DeletePage(page_index);
+  pDoc->SetPageToNullObject(page_obj_num);
 }
 
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_context.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_context.cpp
index ad94b24..7f4753d 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_context.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_context.cpp
@@ -279,11 +279,11 @@
   return nullptr;
 }
 
-void CPDFXFA_Context::DeletePage(int page_index) {
+uint32_t CPDFXFA_Context::DeletePage(int page_index) {
   // Delete from the document first because, if GetPage was never called for
   // this |page_index| then |m_XFAPageList| may have size < |page_index| even
   // if it's a valid page in the document.
-  m_pPDFDoc->DeletePage(page_index);
+  uint32_t page_obj_num = m_pPDFDoc->DeletePage(page_index);
 
   if (fxcrt::IndexInBounds(m_XFAPageList, page_index)) {
     m_XFAPageList.erase(m_XFAPageList.begin() + page_index);
@@ -293,6 +293,8 @@
       }
     }
   }
+
+  return page_obj_num;
 }
 
 bool CPDFXFA_Context::ContainsExtensionForm() const {
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_context.h b/fpdfsdk/fpdfxfa/cpdfxfa_context.h
index a8b563e..dd600c3 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_context.h
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_context.h
@@ -69,7 +69,7 @@
 
   // CPDF_Document::Extension:
   int GetPageCount() const override;
-  void DeletePage(int page_index) override;
+  uint32_t DeletePage(int page_index) override;
   bool ContainsExtensionForm() const override;
   bool ContainsExtensionFullForm() const override;
   bool ContainsExtensionForegroundForm() const override;