diff --git a/string.hpp b/string.hpp
index fc531b12..a1bf4bbb 100644
--- a/string.hpp
+++ b/string.hpp
@@ -40,7 +40,7 @@ namespace cruft {
     /// Apply a functor to each character of a string and return the result.
     template <typename FunctionT>
     std::string
-    transform (std::string const &val, FunctionT &&func)
+    transform (std::string_view val, FunctionT &&func)
     {
         std::string res;
         res.reserve (val.size ());
@@ -56,6 +56,13 @@ namespace cruft {
     }
 
 
+    inline std::string
+    to_upper (std::string_view const &val)
+    {
+        return transform (val, ::toupper);
+    }
+
+
     /// Convert the provided string to all upper case
     inline std::string
     to_upper (std::string &&val)