diff --git a/src/Dates.cpp b/src/Dates.cpp
index 34519e465..203d11e22 100644
--- a/src/Dates.cpp
+++ b/src/Dates.cpp
@@ -386,12 +386,12 @@ bool namedDates (const std::string& name, Variant& value)
 
     if (Lexer::isDigit (name[1]))
     {
-      number = strtol (name.substr (0, 2).c_str (), NULL, 10);
+      number = std::stoi (name.substr (0, 2));
       ordinal = Lexer::lowerCase (name.substr (2));
     }
     else
     {
-      number = strtol (name.substr (0, 1).c_str (), NULL, 10);
+      number = std::stoi (name.substr (0, 1));
       ordinal = Lexer::lowerCase (name.substr (1));
     }