diff --git a/opttest.pl b/opttest.pl
deleted file mode 100755
index 85e3b494..00000000
--- a/opttest.pl
+++ /dev/null
@@ -1,50 +0,0 @@
-#!/usr/bin/perl -w
-use strict;
-use Test;
-
-use vars qw($dir $file $prog $idx $state $output %progs @dirs);
-
-my $tests = 0;
-
-@dirs = qw(plugins plugins-scripts);
-
-foreach $dir (@dirs) {
-	opendir(DIR, $dir) || die "can't opendir $dir: $!";
-	while ($file = readdir(DIR)) {
-		if (-x "$dir/$file" && -f "$dir/$file") {
-			$tests++;
-			$progs{"$dir/$file"} = $file;
-		}
-	}
-	closedir DIR;
-}
-
-plan tests => $tests;
-
-for $prog (keys %progs) {
-	$state = 0;
-	$file = `basename $prog`;
-
-	$idx = 1;
-	$output = `$prog -h 2>&1`;
-	if($?) {$state++;print "$prog failed test $idx\n";}
-	unless ($output =~ m/$progs{$prog}/ms) {
-		$idx++; $state++;print "$output\n$prog failed test $idx\n";
-	}
-
-	$idx++;
-	`$prog --help 2>&1 > /dev/null`;
-	if($?) {$state++;print "$prog failed test $idx\n";}
-
-	$idx++;
-		`$prog -V 2>&1 > /dev/null`;
-	if($?) {$state++;print "$prog failed test $idx\n";}
-
-	$idx++;
-	`$prog --version 2>&1 > /dev/null`;
-	if($?) {$state++;print "$prog failed test $idx\n";}
-
-	print "$prog ($idx tests) ";
-	ok $state,0;
-}
-
diff --git a/plugins-scripts/check_sensors.sh b/plugins-scripts/check_sensors.sh
old mode 100755
new mode 100644
index 866e0e0f..ba3581b1
--- a/plugins-scripts/check_sensors.sh
+++ b/plugins-scripts/check_sensors.sh
@@ -20,7 +20,6 @@ print_help() {
 	echo "This plugin checks hardware status using the lm_sensors package."
 	echo ""
 	support
-	exit "$STATE_OK"
 }
 
 case "$1" in
diff --git a/plugins/negate.c b/plugins/negate.c
index 7e52fe67..750c0bfb 100644
--- a/plugins/negate.c
+++ b/plugins/negate.c
@@ -133,11 +133,11 @@ static const char **process_arguments(int argc, char **argv) {
 			break;
 		case 'h': /* help */
 			print_help();
-			exit(EXIT_SUCCESS);
+			exit(STATE_UNKNOWN);
 			break;
 		case 'V': /* version */
 			print_revision(progname, NP_VERSION);
-			exit(EXIT_SUCCESS);
+			exit(STATE_UNKNOWN);
 		case 't': /* timeout period */
 			if (!is_integer(optarg))
 				usage2(_("Timeout interval must be a positive integer"), optarg);
diff --git a/tools/opttest.pl b/tools/opttest.pl
new file mode 100755
index 00000000..98213082
--- /dev/null
+++ b/tools/opttest.pl
@@ -0,0 +1,74 @@
+#!/usr/bin/perl -w
+use strict;
+use warnings;
+use Test;
+
+# This script (when executed from the monitoring plugins top level directory)
+# executes all the plugins with -h, --help, -V and --version to verify that
+# all of them exit properly with the state UNKNOWN (3)
+
+use vars qw($dir $file $prog $idx $state $output %progs @dirs);
+
+my $tests = 0;
+
+@dirs = qw(plugins plugins-scripts);
+
+foreach my $dir (@dirs) {
+	opendir(DIR, $dir) || die "can't opendir $dir: $!";
+	while ($file = readdir(DIR)) {
+		if (-x "$dir/$file" && -f "$dir/$file") {
+			$tests++;
+			$progs{"$dir/$file"} = $file;
+		}
+	}
+	closedir DIR;
+}
+
+plan tests => $tests;
+
+for my $prog (keys %progs) {
+	$state = 0;
+	$file = `basename $prog`;
+
+	$idx = 1;
+	$output = `$prog -h 2>&1`;
+	if(($? >> 8) != 3) {
+		$state++;
+		print "$prog failed test $idx (help exit code (short form))\n";
+		exit(1);
+	}
+
+	unless ($output =~ m/$progs{$prog}/ms) {
+		$idx++;
+		$state++;
+		print "$output\n$prog failed test $idx\n";
+	}
+
+	$idx++;
+	`$prog --help 2>&1 > /dev/null`;
+	if(($? >> 8) != 3) {
+		$state++;
+		print "$prog failed test $idx (help exit code (long form))\n";
+		exit(1);
+	}
+
+	$idx++;
+	`$prog -V 2>&1 > /dev/null`;
+	if(($? >> 8) != 3) {
+		$state++;
+		print "$prog failed test $idx (version exit code (short form))\n";
+		exit(1);
+	}
+
+	$idx++;
+	`$prog --version 2>&1 > /dev/null`;
+	if(($? >> 8) != 3) {
+		$state++;
+		print "$prog failed test $idx (version exit code (long form))\n";
+		exit(1);
+	}
+
+	print "$prog ($idx tests) ";
+	ok $state,0;
+}
+