Index: uspace/lib/cpp/include/internal/string.hpp
===================================================================
--- uspace/lib/cpp/include/internal/string.hpp	(revision c439e6a7b131ddc747573ef474654a05af44b4f4)
+++ uspace/lib/cpp/include/internal/string.hpp	(revision 5d235bf03d97ae5d6d37afe65b9b285409fb500c)
@@ -83,5 +83,5 @@
     template<class Char, class Traits, class Allocator>
     basic_ostream<Char, Traits>& operator<<(basic_ostream<Char, Traits>& os,
-                                            basic_string<Char, Traits, Allocator>& str)
+                                            const basic_string<Char, Traits, Allocator>& str)
     {
         // TODO: determine padding as described in 27.7.3.6.1