diff --git a/AUTHORS b/AUTHORS
index d3c30ba..0689774 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -14,6 +14,7 @@
 Abdelkarim Sellamna <abdelkarim.se@gmail.com>
 Aleksei Skotnikov <fineaskotnikov@gmail.com>
 Antonio Gomes <tonikitoo@igalia.com>
+Chenguang Shao <chenguangshao1@gmail.com>
 Chery Cherian <cherycherian@gmail.com>
 Claudio DeSouza <claudiomdsjr@gmail.com>
 Dan Ilan <danilan@gmail.com>
diff --git a/fpdfsdk/fpdf_formfill_embeddertest.cpp b/fpdfsdk/fpdf_formfill_embeddertest.cpp
index 2842ec3..71bede8 100644
--- a/fpdfsdk/fpdf_formfill_embeddertest.cpp
+++ b/fpdfsdk/fpdf_formfill_embeddertest.cpp
@@ -3292,6 +3292,41 @@
   CheckCanRedo(false);
 }
 
+TEST_F(FPDFFormFillTextFormEmbedderTest, ContinuouslyReplaceAndKeepSelection) {
+  ScopedFPDFWideString text_to_insert1 = GetFPDFWideString(L"UVW");
+
+  ClickOnFormFieldAtPoint(RegularFormBegin());
+  CheckFocusedFieldText(L"");
+  CheckCanUndo(false);
+  CheckCanRedo(false);
+
+  FORM_ReplaceAndKeepSelection(form_handle(), page(), text_to_insert1.get());
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"UVW");
+
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+
+  PerformUndo();
+  CheckFocusedFieldText(L"");
+
+  CheckCanUndo(false);
+  CheckCanRedo(true);
+  PerformRedo();
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"");
+
+  ScopedFPDFWideString text_to_insert2 = GetFPDFWideString(L"XYZ");
+  FORM_ReplaceAndKeepSelection(form_handle(), page(), text_to_insert2.get());
+  CheckFocusedFieldText(L"UVWXYZ");
+  CheckSelection(L"XYZ");
+
+  CheckCanUndo(true);
+  PerformUndo();
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"");
+}
+
 TEST_F(FPDFFormFillTextFormEmbedderTest, ReplaceSelection) {
   ScopedFPDFWideString text_to_insert = GetFPDFWideString(L"XYZ");
   ClickOnFormFieldAtPoint(RegularFormBegin());
@@ -3340,6 +3375,42 @@
   CheckCanRedo(false);
 }
 
+TEST_F(FPDFFormFillTextFormEmbedderTest, ContinuouslyReplaceSelection) {
+  ScopedFPDFWideString text_to_insert1 = GetFPDFWideString(L"UVW");
+
+  ClickOnFormFieldAtPoint(RegularFormBegin());
+  CheckFocusedFieldText(L"");
+  CheckCanUndo(false);
+  CheckCanRedo(false);
+
+  FORM_ReplaceSelection(form_handle(), page(), text_to_insert1.get());
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"");
+
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+
+  PerformUndo();
+  CheckFocusedFieldText(L"");
+
+  CheckCanUndo(false);
+  CheckCanRedo(true);
+  PerformRedo();
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"");
+
+  ScopedFPDFWideString text_to_insert2 = GetFPDFWideString(L"XYZ");
+  FORM_ReplaceSelection(form_handle(), page(), text_to_insert2.get());
+  CheckFocusedFieldText(L"UVWXYZ");
+
+  CheckCanUndo(true);
+  CheckCanRedo(false);
+
+  PerformUndo();
+  CheckFocusedFieldText(L"UVW");
+  CheckSelection(L"");
+}
+
 TEST_F(FPDFFormFillTextFormEmbedderTest, SelectAllWithKeyboardShortcut) {
   // Start with a couple of letters in the text form.
   TypeTextIntoTextField(2, RegularFormBegin());
diff --git a/fpdfsdk/pwl/cpwl_edit_impl.cpp b/fpdfsdk/pwl/cpwl_edit_impl.cpp
index ba4f43d..92c35f8 100644
--- a/fpdfsdk/pwl/cpwl_edit_impl.cpp
+++ b/fpdfsdk/pwl/cpwl_edit_impl.cpp
@@ -196,6 +196,11 @@
   return m_nCurUndoPos < m_UndoItemStack.size();
 }
 
+CPWL_EditImpl::UndoItemIface* CPWL_EditImpl::UndoStack::GetLastAddItem() {
+  CHECK(!m_UndoItemStack.empty());
+  return m_UndoItemStack.back().get();
+}
+
 void CPWL_EditImpl::UndoStack::Redo() {
   DCHECK(!m_bWorking);
   m_bWorking = true;
@@ -349,25 +354,32 @@
                                                           bool bIsEnd)
     : m_pEdit(pEdit), m_bEnd(bIsEnd) {
   DCHECK(m_pEdit);
+  // Redo ClearSelection, InsertText and ReplaceSelection's end marker
+  // Undo InsertText, ClearSelection and ReplaceSelection's beginning
+  // marker
+  set_undo_remaining(3);
 }
 
 CPWL_EditImpl::UndoReplaceSelection::~UndoReplaceSelection() = default;
 
 int CPWL_EditImpl::UndoReplaceSelection::Redo() {
   m_pEdit->SelectNone();
-  if (IsEnd())
+  if (IsEnd()) {
     return 0;
-  // Redo ClearSelection, InsertText and ReplaceSelection's end marker
-  return 3;
+  }
+  // Redo ClearSelection, InsertText and ReplaceSelection's end
+  // marker. (ClearSelection may not exist)
+  return undo_remaining();
 }
 
 int CPWL_EditImpl::UndoReplaceSelection::Undo() {
   m_pEdit->SelectNone();
-  if (!IsEnd())
+  if (!IsEnd()) {
     return 0;
+  }
   // Undo InsertText, ClearSelection and ReplaceSelection's beginning
-  // marker
-  return 3;
+  // marker. (ClearSelection may not exist)
+  return undo_remaining();
 }
 
 class CPWL_EditImpl::UndoBackspace final : public CPWL_EditImpl::UndoItemIface {
@@ -1770,8 +1782,12 @@
 
 void CPWL_EditImpl::ReplaceAndKeepSelection(const WideString& text) {
   AddEditUndoItem(std::make_unique<UndoReplaceSelection>(this, false));
-  ClearSelection();
-
+  bool is_insert_undo_clear = ClearSelection();
+  // It is necessary to determine whether the value of `m_nUndoRemain` is 2 or 3
+  // based on ClearSelection().
+  if (!is_insert_undo_clear) {
+    m_Undo.GetLastAddItem()->set_undo_remaining(2);
+  }
   // Select the inserted text.
   CPVT_WordPlace caret_before_insert = m_wpCaret;
   InsertText(text, FX_Charset::kDefault);
@@ -1779,13 +1795,24 @@
   m_SelState.Set(caret_before_insert, caret_after_insert);
 
   AddEditUndoItem(std::make_unique<UndoReplaceSelection>(this, true));
+  if (!is_insert_undo_clear) {
+    m_Undo.GetLastAddItem()->set_undo_remaining(2);
+  }
 }
 
 void CPWL_EditImpl::ReplaceSelection(const WideString& text) {
   AddEditUndoItem(std::make_unique<UndoReplaceSelection>(this, false));
-  ClearSelection();
+  bool is_insert_undo_clear = ClearSelection();
+  // It is necessary to determine whether the value of `m_nUndoRemain` is 2 or 3
+  // based on ClearSelection().
+  if (!is_insert_undo_clear) {
+    m_Undo.GetLastAddItem()->set_undo_remaining(2);
+  }
   InsertText(text, FX_Charset::kDefault);
   AddEditUndoItem(std::make_unique<UndoReplaceSelection>(this, true));
+  if (!is_insert_undo_clear) {
+    m_Undo.GetLastAddItem()->set_undo_remaining(2);
+  }
 }
 
 bool CPWL_EditImpl::Redo() {
diff --git a/fpdfsdk/pwl/cpwl_edit_impl.h b/fpdfsdk/pwl/cpwl_edit_impl.h
index 0b3bc76..245bc6c 100644
--- a/fpdfsdk/pwl/cpwl_edit_impl.h
+++ b/fpdfsdk/pwl/cpwl_edit_impl.h
@@ -186,13 +186,23 @@
     // Undo/Redo the current undo item and returns the number of additional
     // items to be processed in |m_UndoItemStack| to fully undo/redo the action.
     // (An example is UndoReplaceSelection::Undo(), if UndoReplaceSelection
-    // marks the end of a replace action, UndoReplaceSelection::Undo() returns 3
-    // because 3 more undo items need to be processed to revert the replace
-    // action: insert text, clear selection and the UndoReplaceSelection which
-    // marks the beginning of replace action.) Implementations should return 0
-    // by default.
+    // marks the end of a replace action, UndoReplaceSelection::Undo() returns
+    // |undo_remaining_|. The default value of |undo_remaining_| in
+    // UndoReplaceSelection is 3. because 3 more undo items need to be processed
+    // to revert the replace action: insert text, clear selection and the
+    // UndoReplaceSelection which marks the beginning of replace action. If
+    // CPWL_EditImpl::ClearSelection() returns false, the value of
+    // |undo_remaining_| in UndoReplaceSelection needs to be set to 2)
+    // Implementations should return 0 by default.
     virtual int Undo() = 0;
     virtual int Redo() = 0;
+    void set_undo_remaining(int undo_remaining) {
+      undo_remaining_ = undo_remaining;
+    }
+    int undo_remaining() const { return undo_remaining_; }
+
+   private:
+    int undo_remaining_ = 0;
   };
 
   class UndoStack {
@@ -205,6 +215,9 @@
     void Redo();
     bool CanUndo() const;
     bool CanRedo() const;
+    // GetLastAddItem() will never return null, so it can only be called after
+    // calling AddItem().
+    UndoItemIface* GetLastAddItem();
 
    private:
     void RemoveHeads();