*8OPINION

Matthews, who had pleaded guilty to the charge of uttering a forged instrument, appeals from an order denying his second petition for post-conviction relief premised on the contention that his guilty plea was involuntarily entered. Since his first post-conviction petition did not challenge the voluntariness of his plea, and since his second petition did not explain why he had previously failed to assert such challenge, the district court denied relief. This was permissible. Rogers v. Warden, 86 Nev. 359, 468 P.2d 993 (1970); Johnson v. Warden, 89 Nev. 476, 515 P.2d 63 (1973).

Affirmed.