diff --git a/fpdfsdk/pwl/cpwl_edit.cpp b/fpdfsdk/pwl/cpwl_edit.cpp
index a6f6f2a..4558e43 100644
--- a/fpdfsdk/pwl/cpwl_edit.cpp
+++ b/fpdfsdk/pwl/cpwl_edit.cpp
@@ -340,14 +340,26 @@
 }
 
 void CPWL_Edit::OnKillFocus() {
+  ObservedPtr observed_ptr = ObservedPtr(this);
   CPWL_ScrollBar* pScroll = GetVScrollBar();
   if (pScroll && pScroll->IsVisible()) {
     pScroll->SetVisible(false);
+    if (!observed_ptr)
+      return;
+
     Move(m_rcOldWindow, true, true);
   }
+  if (!observed_ptr)
+    return;
 
   m_pEdit->SelectNone();
+  if (!observed_ptr)
+    return;
+
   SetCaret(false, CFX_PointF(), CFX_PointF());
+  if (!observed_ptr)
+    return;
+
   SetCharSet(FX_CHARSET_ANSI);
   m_bFocus = false;
 }
diff --git a/fpdfsdk/pwl/cpwl_wnd.cpp b/fpdfsdk/pwl/cpwl_wnd.cpp
index 53c692d..e26df4d 100644
--- a/fpdfsdk/pwl/cpwl_wnd.cpp
+++ b/fpdfsdk/pwl/cpwl_wnd.cpp
@@ -44,7 +44,7 @@
 
 PWL_CREATEPARAM::PWL_CREATEPARAM(const PWL_CREATEPARAM& other) = default;
 
-class CPWL_MsgControl {
+class CPWL_MsgControl : public CFX_Observable<CPWL_MsgControl> {
   friend class CPWL_Wnd;
 
  public:
@@ -96,9 +96,12 @@
   }
 
   void KillFocus() {
+    ObservedPtr observed_ptr = ObservedPtr(this);
     if (!m_aKeyboardPath.empty())
       if (CPWL_Wnd* pWnd = m_aKeyboardPath[0])
         pWnd->OnKillFocus();
+    if (!observed_ptr)
+      return;
 
     m_pMainKeyboardWnd = nullptr;
     m_aKeyboardPath.clear();