Document c++ standard support
diff --git a/README.md b/README.md
index 9e397f2..5fd02a9 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@
 cxx = "0.3"
 ```
 
-*Compiler support: requires rustc 1.42+*<br>
+*Compiler support: requires rustc 1.42+ and c++11 or newer*<br>
 *[Release notes](https://github.com/dtolnay/cxx/releases)*
 
 <br>
diff --git a/src/lib.rs b/src/lib.rs
index 23f2d60..5ebc119 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,7 @@
 //!
 //! <br>
 //!
-//! *Compiler support: requires rustc 1.42+*<br>
+//! *Compiler support: requires rustc 1.42+ and c++11 or newer*<br>
 //! *[Release notes](https://github.com/dtolnay/cxx/releases)*
 //!
 //! <br>