diff --git a/doc/configuration.txt b/doc/configuration.txt
index 1fbe45272..674134e10 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -11754,6 +11754,10 @@ agent-port <port>
 
   See also the "agent-check" and "agent-inter" parameters.
 
+allow-0rtt
+  Allow sending early data to the server when using TLS 1.3.
+  Note that early data will be sent only if the client used early data.
+
 alpn <protocols>
   This enables the TLS ALPN extension and advertises the specified protocol
   list as supported on top of ALPN. The protocol list consists in a comma-