diff --git a/fxjs/ijs_runtime.cpp b/fxjs/ijs_runtime.cpp
index afbdaef..50abd39 100644
--- a/fxjs/ijs_runtime.cpp
+++ b/fxjs/ijs_runtime.cpp
@@ -13,6 +13,13 @@
 #include "fxjs/cjs_runtime.h"
 #endif
 
+IJS_Runtime::ScopedEventContext::ScopedEventContext(IJS_Runtime* pRuntime)
+    : m_pRuntime(pRuntime), m_pContext(pRuntime->NewEventContext()) {}
+
+IJS_Runtime::ScopedEventContext::~ScopedEventContext() {
+  m_pRuntime->ReleaseEventContext(m_pContext.Release());
+}
+
 // static
 void IJS_Runtime::Initialize(unsigned int slot, void* isolate) {
 #ifdef PDF_ENABLE_V8
diff --git a/fxjs/ijs_runtime.h b/fxjs/ijs_runtime.h
index 9f15aba..d74bb94 100644
--- a/fxjs/ijs_runtime.h
+++ b/fxjs/ijs_runtime.h
@@ -11,6 +11,7 @@
 
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/unowned_ptr.h"
 #include "third_party/base/optional.h"
 
 #ifdef PDF_ENABLE_XFA
@@ -36,17 +37,15 @@
 
   class ScopedEventContext {
    public:
-    explicit ScopedEventContext(IJS_Runtime* pRuntime)
-        : m_pRuntime(pRuntime), m_pContext(pRuntime->NewEventContext()) {}
+    explicit ScopedEventContext(IJS_Runtime* pRuntime);
+    ~ScopedEventContext();
 
-    ~ScopedEventContext() { m_pRuntime->ReleaseEventContext(m_pContext); }
-
-    IJS_EventContext* Get() const { return m_pContext; }
-    IJS_EventContext* operator->() const { return m_pContext; }
+    IJS_EventContext* Get() const { return m_pContext.Get(); }
+    IJS_EventContext* operator->() const { return m_pContext.Get(); }
 
    private:
-    IJS_Runtime* m_pRuntime;
-    IJS_EventContext* m_pContext;
+    UnownedPtr<IJS_Runtime> m_pRuntime;
+    UnownedPtr<IJS_EventContext> m_pContext;
   };
 
   static void Initialize(unsigned int slot, void* isolate);