diff --git a/src/polyp/polypaudio.h b/src/polyp/polypaudio.h
index 5dd7aa103..1830dea86 100644
--- a/src/polyp/polypaudio.h
+++ b/src/polyp/polypaudio.h
@@ -54,6 +54,11 @@
  * \li The complete but somewhat complicated to use asynchronous API
  * \li The simplified, easy to use, but limited synchronous API
  *
+ * All strings in Polypaudio are in the UTF-8 encoding, regardless of current
+ * locale. Some functions will filter invalid sequences from the string, some
+ * will simply fail. To ensure reliable behaviour, make sure everything you
+ * pass to the API is already in UTF-8.
+ 
  * \section simple_sec Simple API
  *
  * Use this if you develop your program in synchronous style and just