diff --git a/include/asterisk/frame.h b/include/asterisk/frame.h
index 73fdef664a..1a66068c3b 100644
--- a/include/asterisk/frame.h
+++ b/include/asterisk/frame.h
@@ -421,7 +421,7 @@ void ast_swapcopy_samples(void *dst, const void *src, int samples);
 
 /*! \brief Get the name of a format
  * \param format id of format
- * \return A static string containing the name of the format or "UNKN" if unknown.
+ * \return A static string containing the name of the format or "unknown" if unknown.
  */
 char* ast_getformatname(int format);