diff --git a/README.md b/README.md
index c76fe23..f06defc 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 This library provides a high-level Text-To-Speech (TTS) interface supporting various backends. Currently supported backends are:
 
 * Windows
-  * Screen readers/SAPI via Tolk
+  * Screen readers/SAPI via Tolk (requires `use_tolk` Cargo feature)
   * WinRT
 * Linux via [Speech Dispatcher](https://freebsoft.org/speechd)
 * MacOS
diff --git a/src/lib.rs b/src/lib.rs
index c6a7a58..46ad4c8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,7 +2,7 @@
  * a Text-To-Speech (TTS) library providing high-level interfaces to a variety of backends.
  * Currently supported backends are:
  * * Windows
- *   * Screen readers/SAPI via Tolk
+ *   * Screen readers/SAPI via Tolk (requires `use_tolk` Cargo feature)
  *   * WinRT
  * * Linux via [Speech Dispatcher](https://freebsoft.org/speechd)
  * * MacOS