diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 4f526d4..288627b 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -220,7 +220,9 @@
 #endif
 
 /*
- * Size of the input / output buffer.
+ * Maxium fragment length in bytes,
+ * determines the size of each of the two internal I/O buffers.
+ *
  * Note: the RFC defines the default size of SSL / TLS messages. If you
  * change the value here, other clients / servers may not be able to
  * communicate with you anymore. Only change this value if you control