diff --git a/doc/api.rst b/doc/api.rst
index d7bdd349..c5a0ec86 100644
--- a/doc/api.rst
+++ b/doc/api.rst
@@ -69,6 +69,7 @@ checked at compile time in C++20. To pass a runtime format string wrap it in
 Compile-time Format String Checks
 ---------------------------------
 
+Requires C++14 and it's no-op in C++11.
 Compile-time checks are enabled when using ``FMT_STRING``. They support built-in
 and string types as well as user-defined types with ``constexpr`` ``parse``
 functions in their ``formatter`` specializations.