diff --git a/bin/nsupdate/nsupdate.8 b/bin/nsupdate/nsupdate.8
index 849a1803c6..e1b8fe0671 100644
--- a/bin/nsupdate/nsupdate.8
+++ b/bin/nsupdate/nsupdate.8
@@ -13,7 +13,7 @@
 .\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 .\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.\" $Id: nsupdate.8,v 1.5 2000/08/15 19:40:40 gson Exp $
+.\" $Id: nsupdate.8,v 1.6 2000/08/15 19:47:06 bwelling Exp $
 .\"
 .Dd Jun 30, 2000
 .Dt NSUPDATE 8
@@ -97,8 +97,9 @@ With the
 option,
 .Nm nsupdate
 reads the shared secret from the file
-.Ar keyfile .
-When the
+.Ar keyfile ,
+whose name is of the form K{name}.+157.+{random}.private .  For historical
+reasons, the file K{name}.+157.+{random}.key must also be present.  When the
 .Fl y
 is used, a signature is generated from
 .Ar keyname:secret.
diff --git a/doc/man/bin/nsupdate.8 b/doc/man/bin/nsupdate.8
index 849a1803c6..e1b8fe0671 100644
--- a/doc/man/bin/nsupdate.8
+++ b/doc/man/bin/nsupdate.8
@@ -13,7 +13,7 @@
 .\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 .\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.\" $Id: nsupdate.8,v 1.5 2000/08/15 19:40:40 gson Exp $
+.\" $Id: nsupdate.8,v 1.6 2000/08/15 19:47:06 bwelling Exp $
 .\"
 .Dd Jun 30, 2000
 .Dt NSUPDATE 8
@@ -97,8 +97,9 @@ With the
 option,
 .Nm nsupdate
 reads the shared secret from the file
-.Ar keyfile .
-When the
+.Ar keyfile ,
+whose name is of the form K{name}.+157.+{random}.private .  For historical
+reasons, the file K{name}.+157.+{random}.key must also be present.  When the
 .Fl y
 is used, a signature is generated from
 .Ar keyname:secret.