diff --git a/sum.cpp b/sum.cpp
index f6de3e0..efd1b27 100644
--- a/sum.cpp
+++ b/sum.cpp
@@ -1,4 +1,7 @@
 #include <cassert>
+#include <string>
+
+using namespace std::string_literals;
 
 template <typename T> auto sum(T final) { return final; }
 template <typename T, typename... Ts> auto sum(T first, Ts... rem) {
@@ -11,4 +14,7 @@ int main(void) {
   assert(dummy);
   dummy = sum<double>(1.5, 1, 2, 3.5) == 8.0;
   assert(dummy);
+  dummy = sum<std::string>("asdf"s, "abcdefghijklmnop"s, "qrstuvwxyz"s) ==
+          "asdfabcdefghijklmnopqrstuvwxyz"s;
+  assert(dummy);
 }