diff --git a/man/ccr.1 b/man/ccr.1
index 1625e82..0689af9 100644
--- a/man/ccr.1
+++ b/man/ccr.1
@@ -94,7 +94,8 @@ decrypt it.
 
 .TP
 \fB\-u\fR, \fB\-\-user\fR <\fIkeyspec\fR>
-Specify a private key to use for signing the message.
+Specify a private key to use for signing the message. If this option is empty,
+it is defaulted from CCR_USER environment variable.
 
 .TP
 \fB\-C\fR, \fB\-\-cleartext\fR