diff --git a/include/nonstd/string_view.hpp b/include/nonstd/string_view.hpp
index 84a565f..5f1fccf 100644
--- a/include/nonstd/string_view.hpp
+++ b/include/nonstd/string_view.hpp
@@ -134,6 +134,8 @@
 
 #if nssv_CONFIG_CONVERSION_STD_STRING_FREE_FUNCTIONS
 
+#include <string>
+
 namespace nonstd {
 
 template< class CharT, class Traits, class Allocator = std::allocator<CharT> >