diff --git a/ACE/ace/SString.cpp b/ACE/ace/SString.cpp
index abd86b337cb53..40ffed47baf0c 100644
--- a/ACE/ace/SString.cpp
+++ b/ACE/ace/SString.cpp
@@ -21,7 +21,7 @@ ACE_BEGIN_VERSIONED_NAMESPACE_DECL
 ACE_OSTREAM_TYPE &
 operator<< (ACE_OSTREAM_TYPE &os, const ACE_CString &cs)
 {
-  if (cs.fast_rep () != 0)
+  if (cs.fast_rep ())
     os << cs.fast_rep ();
   return os;
 }
@@ -59,7 +59,7 @@ ACE_NS_WString::char_rep () const
     return 0;
   else
     {
-      char *t = 0;
+      char *t = nullptr;
 
 #if defined (ACE_HAS_ALLOC_HOOKS)
       ACE_ALLOCATOR_RETURN (t,
@@ -89,7 +89,7 @@ ACE_NS_WString::ushort_rep () const
     return 0;
   else
     {
-      ACE_UINT16 *t = 0;
+      ACE_UINT16 *t = nullptr;
 
 #if defined (ACE_HAS_ALLOC_HOOKS)
       ACE_ALLOCATOR_RETURN (t,
diff --git a/ACE/ace/SString.h b/ACE/ace/SString.h
index 1473c2dee2632..fc9210c2b083e 100644
--- a/ACE/ace/SString.h
+++ b/ACE/ace/SString.h
@@ -275,16 +275,17 @@ typedef ACE_CString ACE_TString;
 class ACE_Export ACE_Auto_String_Free
 {
 public:
-  explicit ACE_Auto_String_Free (char* p = 0);
+  explicit ACE_Auto_String_Free (char* p = nullptr);
   ACE_Auto_String_Free (ACE_Auto_String_Free &rhs);
   ACE_Auto_String_Free& operator= (ACE_Auto_String_Free &rhs);
   ~ACE_Auto_String_Free ();
 
   char* operator* () const;
   char operator[] (size_t i) const;
+  explicit operator bool () const;
   char* get () const;
   char* release ();
-  void reset (char* p = 0);
+  void reset (char* p = nullptr);
 
 private:
   char* p_;
diff --git a/ACE/ace/SString.inl b/ACE/ace/SString.inl
index 1757425725c9a..8a4e1695eda81 100644
--- a/ACE/ace/SString.inl
+++ b/ACE/ace/SString.inl
@@ -231,7 +231,7 @@ ACE_INLINE
 ACE_Auto_String_Free::ACE_Auto_String_Free (ACE_Auto_String_Free& rhs)
   :  p_ (rhs.p_)
 {
-  rhs.p_ = 0;
+  rhs.p_ = nullptr;
 }
 
 ACE_INLINE void
@@ -251,7 +251,7 @@ ACE_Auto_String_Free::operator= (ACE_Auto_String_Free& rhs)
   if (this != &rhs)
     {
       this->reset (rhs.p_);
-      rhs.p_ = 0;
+      rhs.p_ = nullptr;
     }
   return *this;
 }
@@ -274,6 +274,12 @@ ACE_Auto_String_Free::operator[] (size_t i) const
   return this->p_[i];
 }
 
+ACE_INLINE
+ACE_Auto_String_Free::operator bool (void) const
+{
+  return this->p_ != nullptr;
+}
+
 ACE_INLINE char*
 ACE_Auto_String_Free::get () const
 {
@@ -284,7 +290,7 @@ ACE_INLINE char*
 ACE_Auto_String_Free::release ()
 {
   char* p = this->p_;
-  this->p_ = 0;
+  this->p_ = nullptr;
   return p;
 }
 
diff --git a/ACE/tests/SString_Test.cpp b/ACE/tests/SString_Test.cpp
index 793bf6a5df6fe..796634306c4b1 100644
--- a/ACE/tests/SString_Test.cpp
+++ b/ACE/tests/SString_Test.cpp
@@ -150,6 +150,33 @@ int testConstIterator()
   return 0;
 }
 
+int testAutoStringFree()
+{
+  char* s = ACE_OS::strdup("Hello, World");
+  const ACE_Auto_String_Free s1(s);
+  if (s1)
+  {
+  }
+  else
+  {
+    ACE_ERROR_RETURN ((LM_ERROR,
+                       ACE_TEXT ("ACE_Auto_String_Free::operator bool return false")),
+                       1);
+  }
+
+  if (!s1)
+    ACE_ERROR_RETURN ((LM_ERROR,
+                       ACE_TEXT ("!ACE_Auto_String_Free::operator bool return true")),
+                       1);
+
+  if (!**s1)
+    ACE_ERROR_RETURN ((LM_ERROR,
+                       ACE_TEXT ("ACE_Auto_String_Free is empty")),
+                       1);
+
+  return 0;
+}
+
 
 int
 run_main (int, ACE_TCHAR *[])
@@ -425,6 +452,7 @@ run_main (int, ACE_TCHAR *[])
   int err = testConcatenation ();
   err += testIterator ();
   err += testConstIterator ();
+  err += testAutoStringFree ();
 
   ACE_END_TEST;
   return err;