diff --git a/ACE/ace/Svc_Conf_Lexer.cpp b/ACE/ace/Svc_Conf_Lexer.cpp
index 371fad474a321..3c408d5e0249d 100644
--- a/ACE/ace/Svc_Conf_Lexer.cpp
+++ b/ACE/ace/Svc_Conf_Lexer.cpp
@@ -34,7 +34,7 @@ ACE_BEGIN_VERSIONED_NAMESPACE_DECL
 # define ACE_TEMPORARY_STRING(X,SIZE) \
    char* X = 0; \
    char X ## buf[ACE_YY_BUF_SIZE]; \
-   std::unique_ptr<char> X ## bufp (0); \
+   std::unique_ptr<char> X ## bufp (nullptr); \
    if (SIZE > ACE_YY_BUF_SIZE) { \
      X ## bufp.reset (new char[SIZE]); \
      X = X ## bufp.get (); \