diff --git a/plugins/sudoers/auth/fwtk.c b/plugins/sudoers/auth/fwtk.c
index 02f3a5ea0..a6e45b253 100644
--- a/plugins/sudoers/auth/fwtk.c
+++ b/plugins/sudoers/auth/fwtk.c
@@ -56,12 +56,12 @@ fwtk_init(struct passwd *pw, char **promptp, sudo_auth *auth)
     char resp[128];			/* Response from the server */
 
     if ((confp = cfg_read("sudo")) == (Cfg *)-1) {
-	warningx(_("cannot read fwtk config"));
+	warningx(_("unable to read fwtk config"));
 	return AUTH_FATAL;
     }
 
     if (auth_open(confp)) {
-	warningx(_("cannot connect to authentication server"));
+	warningx(_("unable to connect to authentication server"));
 	return AUTH_FATAL;
     }
 
diff --git a/plugins/sudoers/auth/sudo_auth.c b/plugins/sudoers/auth/sudo_auth.c
index 103e8f3ba..58ba3ec2b 100644
--- a/plugins/sudoers/auth/sudo_auth.c
+++ b/plugins/sudoers/auth/sudo_auth.c
@@ -132,7 +132,7 @@ verify_user(struct passwd *pw, char *prompt)
     if (standalone && auth_switch[1].name != NULL) {
 	audit_failure(NewArgv, "invalid authentication methods");
     	log_error(0, _("Invalid authentication methods compiled into sudo!  "
-	    "You cannot mix standalone and non-standalone authentication."));
+	    "You may mix standalone and non-standalone authentication."));
 	return -1;
     }
 
diff --git a/plugins/sudoers/iolog.c b/plugins/sudoers/iolog.c
index de23e474b..36f617614 100644
--- a/plugins/sudoers/iolog.c
+++ b/plugins/sudoers/iolog.c
@@ -166,14 +166,14 @@ io_nextid(char *iolog_dir, char sessid[7])
     }
     fd = open(pathbuf, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
     if (fd == -1)
-	log_error(USE_ERRNO, _("cannot open %s"), pathbuf);
+	log_error(USE_ERRNO, _("unable to open %s"), pathbuf);
     lock_file(fd, SUDO_LOCK);
 
     /* Read seq number (base 36). */
     nread = read(fd, buf, sizeof(buf));
     if (nread != 0) {
 	if (nread == -1)
-	    log_error(USE_ERRNO, _("cannot read %s"), pathbuf);
+	    log_error(USE_ERRNO, _("unable to read %s"), pathbuf);
 	id = strtoul(buf, &ep, 36);
 	if (buf == ep || id >= SESSID_MAX)
 	    log_error(0, _("invalid sequence number %s"), pathbuf);
diff --git a/plugins/sudoers/ldap.c b/plugins/sudoers/ldap.c
index 3e7a65664..29822fcf4 100644
--- a/plugins/sudoers/ldap.c
+++ b/plugins/sudoers/ldap.c
@@ -447,11 +447,11 @@ sudo_ldap_parse_uri(const struct ldap_config_list_str *uri_list)
 
 	if (nldaps != 0) {
 	    if (nldap != 0) {
-		warningx(_("cannot mix ldap and ldaps URIs"));
+		warningx(_("unable to mix ldap and ldaps URIs"));
 		goto done;
 	    }
 	    if (ldap_conf.ssl_mode == SUDO_LDAP_STARTTLS) {
-		warningx(_("cannot mix ldaps and starttls"));
+		warningx(_("unable to mix ldaps and starttls"));
 		goto done;
 	    }
 	    ldap_conf.ssl_mode = SUDO_LDAP_SSL;
diff --git a/plugins/sudoers/logging.c b/plugins/sudoers/logging.c
index 71df37b0c..606ead75e 100644
--- a/plugins/sudoers/logging.c
+++ b/plugins/sudoers/logging.c
@@ -451,14 +451,14 @@ send_mail(const char *fmt, ...)
     switch (pid = fork()) {
 	case -1:
 	    /* Error. */
-	    error(1, _("cannot fork"));
+	    error(1, _("unable to fork"));
 	    break;
 	case 0:
 	    /* Child. */
 	    switch (pid = fork()) {
 		case -1:
 		    /* Error. */
-		    mysyslog(LOG_ERR, _("cannot fork: %m"));
+		    mysyslog(LOG_ERR, _("unable to fork: %m"));
 		    _exit(1);
 		case 0:
 		    /* Grandchild continues below. */
@@ -508,14 +508,14 @@ send_mail(const char *fmt, ...)
     (void) sigaction(SIGPIPE, &sa, NULL);
 
     if (pipe(pfd) == -1) {
-	mysyslog(LOG_ERR, _("cannot open pipe: %m"));
+	mysyslog(LOG_ERR, _("unable to open pipe: %m"));
 	_exit(1);
     }
 
     switch (pid = fork()) {
 	case -1:
 	    /* Error. */
-	    mysyslog(LOG_ERR, _("cannot fork: %m"));
+	    mysyslog(LOG_ERR, _("unable to fork: %m"));
 	    _exit(1);
 	    break;
 	case 0:
@@ -527,7 +527,7 @@ send_mail(const char *fmt, ...)
 		/* Child, set stdin to output side of the pipe */
 		if (pfd[0] != STDIN_FILENO) {
 		    if (dup2(pfd[0], STDIN_FILENO) == -1) {
-			mysyslog(LOG_ERR, _("cannot dup stdin: %m"));
+			mysyslog(LOG_ERR, _("unable to dup stdin: %m"));
 			_exit(127);
 		    }
 		    (void) close(pfd[0]);
@@ -561,7 +561,7 @@ send_mail(const char *fmt, ...)
 		set_perms(PERM_FULL_USER|PERM_NOEXIT);
 		execv(mpath, argv);
 #endif /* NO_ROOT_MAILER */
-		mysyslog(LOG_ERR, _("cannot execute %s: %m"), mpath);
+		mysyslog(LOG_ERR, _("unable to execute %s: %m"), mpath);
 		_exit(127);
 	    }
 	    break;
diff --git a/plugins/sudoers/mon_systrace.c b/plugins/sudoers/mon_systrace.c
index a463a7146..c8772848b 100644
--- a/plugins/sudoers/mon_systrace.c
+++ b/plugins/sudoers/mon_systrace.c
@@ -889,7 +889,7 @@ check_execv(fd, pid, seqnr, askp, policyp, errorp)
     if (rval == -1 || getcwd(user_cwd, sizeof(user_cwd)) == NULL) {
 	if (rval == -1 && errno == EBUSY)
 	    return -1;
-	warningx("cannot get working directory");
+	warningx("unable to get working directory");
 	(void) strlcpy(user_cwd, "unknown", sizeof(user_cwd));
     }
 
diff --git a/plugins/sudoers/sudoreplay.c b/plugins/sudoers/sudoreplay.c
index e567966c4..6cada297b 100644
--- a/plugins/sudoers/sudoreplay.c
+++ b/plugins/sudoers/sudoreplay.c
@@ -371,7 +371,7 @@ main(int argc, char *argv[])
 	if (ch != -1)
 	    (void) fcntl(STDIN_FILENO, F_SETFL, ch | O_NONBLOCK);
 	if (!term_raw(STDIN_FILENO, 1))
-	    error(1, _("cannot set tty to raw mode"));
+	    error(1, _("unable to set tty to raw mode"));
     }
     fdsw = (fd_set *)emalloc2(howmany(STDOUT_FILENO + 1, NFDBITS),
 	sizeof(fd_mask));
diff --git a/plugins/sudoers/visudo.c b/plugins/sudoers/visudo.c
index 91f977214..6963c8a97 100644
--- a/plugins/sudoers/visudo.c
+++ b/plugins/sudoers/visudo.c
@@ -362,7 +362,7 @@ edit_sudoers(struct sudoersfile *sp, char *editor, char *args, int lineno)
 	 * Sanity checks.
 	 */
 	if (stat(sp->tpath, &sb) < 0) {
-	    warningx(_("cannot stat temporary file (%s), %s unchanged"),
+	    warningx(_("unable to stat temporary file (%s), %s unchanged"),
 		sp->tpath, sp->path);
 	    return FALSE;
 	}
diff --git a/src/exec.c b/src/exec.c
index 474fcc0f2..bf530b83d 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -244,14 +244,14 @@ sudo_execve(struct command_details *details, struct command_status *cstat)
      * Parent sends signal info to child and child sends back wait status.
      */
     if (socketpair(PF_UNIX, SOCK_DGRAM, 0, sv) == -1)
-	error(1, _("cannot create sockets"));
+	error(1, _("unable to create sockets"));
 
     /*
      * We use a pipe to atomically handle signal notification within
      * the select() loop.
      */
     if (pipe_nonblock(signal_pipe) != 0)
-	error(1, _("cannot create pipe"));
+	error(1, _("unable to create pipe"));
 
     zero_bytes(&sa, sizeof(sa));
     sigemptyset(&sa.sa_mask);
diff --git a/src/exec_pty.c b/src/exec_pty.c
index 801385e44..02227070b 100644
--- a/src/exec_pty.c
+++ b/src/exec_pty.c
@@ -819,7 +819,7 @@ exec_monitor(struct command_details *details, int backchannel)
      * the select() loop.
      */
     if (pipe_nonblock(signal_pipe) != 0)
-	error(1, _("cannot create pipe"));
+	error(1, _("unable to create pipe"));
 
     /* Reset SIGWINCH and SIGALRM. */
     zero_bytes(&sa, sizeof(sa));
diff --git a/src/net_ifs.c b/src/net_ifs.c
index 8814a54f2..4c1ad765b 100644
--- a/src/net_ifs.c
+++ b/src/net_ifs.c
@@ -221,7 +221,7 @@ get_net_ifs(char **addrinfo)
 
     sock = socket(AF_INET, SOCK_DGRAM, 0);
     if (sock < 0)
-	error(1, _("cannot open socket"));
+	error(1, _("unable to open socket"));
 
     /*
      * Get interface configuration or return.
diff --git a/src/selinux.c b/src/selinux.c
index 86a87090c..dc519731a 100644
--- a/src/selinux.c
+++ b/src/selinux.c
@@ -191,7 +191,7 @@ relabel_tty(const char *ttyn, int ptyfd)
 	/* Reopen pty that was relabeled, std{in,out,err} are reset later. */
 	se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY, 0);
 	if (se_state.ttyfd == -1) {
-	    warning(_("cannot open %s"), ttyn);
+	    warning(_("unable to open %s"), ttyn);
 	    if (se_state.enforcing)
 		goto bad;
 	}