diff -up sudo-1.8.6p3/plugins/sudoers/auth/pam.c.authinterrupt sudo-1.8.6p3/plugins/sudoers/auth/pam.c
--- sudo-1.8.6p3/plugins/sudoers/auth/pam.c.authinterrupt	2014-05-22 13:46:31.204706184 +0200
+++ sudo-1.8.6p3/plugins/sudoers/auth/pam.c	2014-05-22 13:47:06.729830043 +0200
@@ -167,13 +167,13 @@ sudo_pam_verify(struct passwd *pw, char
 	    /* FALLTHROUGH */
 	case PAM_AUTH_ERR:
 	case PAM_AUTHINFO_UNAVAIL:
+	case PAM_PERM_DENIED:
 	    if (getpass_error) {
 		/* error or ^C from tgetpass() */
 		debug_return_int(AUTH_INTR);
 	    }
 	    /* FALLTHROUGH */
 	case PAM_MAXTRIES:
-	case PAM_PERM_DENIED:
 	    debug_return_int(AUTH_FAILURE);
 	default:
 	    if ((s = pam_strerror(pamh, *pam_status)))
@@ -343,6 +343,7 @@ converse(int num_msg, PAM_CONST struct p
 		if (pass == NULL) {
 		    /* Error (or ^C) reading password, don't try again. */
 		    getpass_error = 1;
+		    ret = PAM_CONV_ERR;
 #if (defined(__darwin__) || defined(__APPLE__)) && !defined(OPENPAM_VERSION)
 		    pass = "";
 #else