diff --git a/bin/oathkey/oathkey.1 b/bin/oathkey/oathkey.1
index 981b3f3..5b43280 100644
--- a/bin/oathkey/oathkey.1
+++ b/bin/oathkey/oathkey.1
@@ -28,7 +28,7 @@
 .\"
 .\" $Id$
 .\"
-.Dd October 23, 2015
+.Dd January 9, 2016
 .Dt OATHKEY 1
 .Os
 .Sh NAME
@@ -78,7 +78,8 @@ The commands are:
 Compute and display the current code for the given key.
 If a count is specified, compute and display
 .Ar count
-codes in total, starting with the current code.
+codes in total, starting with the current code, up to a maximum of
+1,000 codes.
 If writeback mode is enabled, the user's keyfile is updated to prevent
 reuse.
 .It Cm genkey Ar hotp | totp
diff --git a/bin/oathkey/oathkey.c b/bin/oathkey/oathkey.c
index bbaa0da..40807b3 100644
--- a/bin/oathkey/oathkey.c
+++ b/bin/oathkey/oathkey.c
@@ -297,7 +297,7 @@ oathkey_calc(int argc, char *argv[])
 		return (RET_USAGE);
 	if (argc > 0) {
 		n = strtoul(argv[0], &end, 10);
-		if (end == argv[0] || *end != '\0' || n < 1)
+		if (end == argv[0] || *end != '\0' || n < 1 || n > 1000)
 			return (RET_USAGE);
 	} else {
 		n = 1;