describe diff -uc
diff --git a/man/man1/cvs.1 b/man/man1/cvs.1
index c8daba8..62db389 100644
--- a/man/man1/cvs.1
+++ b/man/man1/cvs.1
@@ -36,7 +36,7 @@
 .I revision
 ]
 [
-.B -u
+.B -cu
 ]
 [
 .I path ...
@@ -152,6 +152,15 @@
 options are given,
 those two versions are compared, and the local copy is ignored.
 .PP
+.I Cvs
+.I diff
+passes the
+.B -u
+or
+.B -c
+options to the Unix
+.IR diff .
+.PP
 If you download a tar file from the web
 instead of checking out the tree with CVS,
 you can still use the