diff --git a/core/fxcrt/cfx_retain_ptr_unittest.cpp b/core/fxcrt/cfx_retain_ptr_unittest.cpp
index 4e74e52..9da0d5c 100644
--- a/core/fxcrt/cfx_retain_ptr_unittest.cpp
+++ b/core/fxcrt/cfx_retain_ptr_unittest.cpp
@@ -208,8 +208,8 @@
   PseudoRetainable obj1;
   CFX_RetainPtr<PseudoRetainable> null_ptr;
   CFX_RetainPtr<PseudoRetainable> obj1_ptr(&obj1);
-  bool null_bool = null_ptr;
-  bool obj1_bool = obj1_ptr;
+  bool null_bool = !!null_ptr;
+  bool obj1_bool = !!obj1_ptr;
   EXPECT_FALSE(null_bool);
   EXPECT_TRUE(obj1_bool);
 }
diff --git a/core/fxcrt/include/cfx_count_ref.h b/core/fxcrt/include/cfx_count_ref.h
index 95132a7..d709efb 100644
--- a/core/fxcrt/include/cfx_count_ref.h
+++ b/core/fxcrt/include/cfx_count_ref.h
@@ -47,7 +47,7 @@
     return m_pObject == that.m_pObject;
   }
   bool operator!=(const CFX_CountRef& that) const { return !(*this == that); }
-  operator bool() const { return m_pObject; }
+  explicit operator bool() const { return !!m_pObject; }
 
  private:
   class CountedObj : public ObjClass {
diff --git a/core/fxcrt/include/cfx_retain_ptr.h b/core/fxcrt/include/cfx_retain_ptr.h
index 25edd58..e40feb6 100644
--- a/core/fxcrt/include/cfx_retain_ptr.h
+++ b/core/fxcrt/include/cfx_retain_ptr.h
@@ -46,7 +46,7 @@
 
   bool operator!=(const CFX_RetainPtr& that) const { return !(*this == that); }
 
-  operator bool() const { return !!m_pObj; }
+  explicit operator bool() const { return !!m_pObj; }
   T& operator*() const { return *m_pObj.get(); }
   T* operator->() const { return m_pObj.get(); }