diff --git a/phosphor-regulators/src/config_file_parser.hpp b/phosphor-regulators/src/config_file_parser.hpp
index a4efff4..3add3ff 100644
--- a/phosphor-regulators/src/config_file_parser.hpp
+++ b/phosphor-regulators/src/config_file_parser.hpp
@@ -350,7 +350,7 @@
     {
         throw std::invalid_argument{"Element is not hexadecimal string"};
     }
-    return static_cast<uint8_t>(std::stoul(value, 0, 0));
+    return static_cast<uint8_t>(std::stoul(value, nullptr, 0));
 }
 
 /**
diff --git a/pmbus.cpp b/pmbus.cpp
index de387d6..e737147 100644
--- a/pmbus.cpp
+++ b/pmbus.cpp
@@ -128,7 +128,7 @@
 
     try
     {
-        char* err = NULL;
+        char* err = nullptr;
         std::string val{1, '\0'};
 
         file.open(path);