diff --git a/include/string_view b/include/string_view
index 4c759ab..c5cc255 100644
--- a/include/string_view
+++ b/include/string_view
@@ -155,10 +155,10 @@
   template <> struct hash<u32string_view>;
   template <> struct hash<wstring_view>;
 
-  constexpr basic_string<char>     operator "" s( const char *str,     size_t len ); // C++17
-  constexpr basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++17
-  constexpr basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++17
-  constexpr basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++17
+  constexpr basic_string_view<char>     operator "" sv( const char *str,     size_t len ) noexcept;
+  constexpr basic_string_view<wchar_t>  operator "" sv( const wchar_t *str,  size_t len ) noexcept;
+  constexpr basic_string_view<char16_t> operator "" sv( const char16_t *str, size_t len ) noexcept;
+  constexpr basic_string_view<char32_t> operator "" sv( const char32_t *str, size_t len ) noexcept;
 
 }  // namespace std
 
@@ -760,25 +760,25 @@
   inline namespace string_view_literals
   {
     inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-    basic_string_view<char> operator "" sv(const char *__str, size_t __len)
+    basic_string_view<char> operator "" sv(const char *__str, size_t __len) _NOEXCEPT
     {
         return basic_string_view<char> (__str, __len);
     }
 
     inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-    basic_string_view<wchar_t> operator "" sv(const wchar_t *__str, size_t __len)
+    basic_string_view<wchar_t> operator "" sv(const wchar_t *__str, size_t __len) _NOEXCEPT
     {
         return basic_string_view<wchar_t> (__str, __len);
     }
 
     inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-    basic_string_view<char16_t> operator "" sv(const char16_t *__str, size_t __len)
+    basic_string_view<char16_t> operator "" sv(const char16_t *__str, size_t __len) _NOEXCEPT
     {
         return basic_string_view<char16_t> (__str, __len);
     }
 
     inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-    basic_string_view<char32_t> operator "" sv(const char32_t *__str, size_t __len)
+    basic_string_view<char32_t> operator "" sv(const char32_t *__str, size_t __len) _NOEXCEPT
     {
         return basic_string_view<char32_t> (__str, __len);
     }