diff --git a/doc/tor.1.in b/doc/tor.1.in
index 08182e977f..dfadfd6892 100644
--- a/doc/tor.1.in
+++ b/doc/tor.1.in
@@ -177,6 +177,10 @@ When a request for address arrives to Tor, it will rewrite it to newaddress befo
 \fBNewCircuitPeriod \fR\fINUM\fP
 Every NUM seconds consider whether to build a new circuit. (Default: 60)
 .TP
+\fBMaxCircuitDirtiness \fR\fINUM\fP
+Feel free to reuse a circuit that was first used at most NUM seconds
+ago, but never attach a new stream to a circuit that is too old.
+.TP
 \fBNodeFamily \fR\fInickname\fR,\fInickname\fR,\fI...\fP
 The named Tor servers constitute a "family" of similar or co-administered
 servers, so never use any two of them in the same circuit. Defining a