diff --git a/lib/Manual.php b/lib/Manual.php
new file mode 100644
index 00000000..a7676f4a
--- /dev/null
+++ b/lib/Manual.php
@@ -0,0 +1,23 @@
+<?
+
+class Manual{
+	public static function GetLatestVersion(){
+		$dirs = glob(MANUAL_PATH . '/*', GLOB_ONLYDIR);
+		sort($dirs);
+		return str_replace(MANUAL_PATH . '/', '', $dirs[sizeof($dirs) - 1]);
+	}
+
+	public static function GetRequestedVersion(){
+		try{
+			if(preg_match_all('|/manual/([0-9]+\.[0-9]+\.[0-9]+)|ius', $_SERVER['REQUEST_URI'], $matches)){
+				return($matches[1][0]);
+			}
+			else{
+				return null;
+			}
+		}
+		catch(\Exception $ex){
+			return null;
+		}
+	}
+}
diff --git a/templates/OldManualVersionWarning.php b/templates/OldManualVersionWarning.php
new file mode 100644
index 00000000..ae33e985
--- /dev/null
+++ b/templates/OldManualVersionWarning.php
@@ -0,0 +1,7 @@
+<? if(Manual::GetRequestedVersion() !== Manual::GetLatestVersion()){ ?>
+<aside class="alert">
+	<p>This is an outdated version of the manual that is no longer current.</p>
+	<p><a href="/manual/latest">Read the latest version instead.</a></p>
+</aside>
+<? } ?>
+
diff --git a/www/css/manual.css b/www/css/manual.css
index 87c21697..f02d341a 100644
--- a/www/css/manual.css
+++ b/www/css/manual.css
@@ -643,6 +643,10 @@ figure code.css{
 	overflow-x: auto;
 }
 
+main.manual aside.alert p{
+	text-align: center;
+}
+
 @media(max-width: 1700px){
 	main.manual > article{
 		margin-left: 10rem;
diff --git a/www/manual/index.php b/www/manual/index.php
index 565e6d1b..9e2fb942 100644
--- a/www/manual/index.php
+++ b/www/manual/index.php
@@ -6,10 +6,7 @@ use function Safe\sort;
 
 // Redirect to the latest version of the manual
 
-$dirs = glob(MANUAL_PATH . '/*', GLOB_ONLYDIR);
-sort($dirs);
-
-$currentManual = str_replace(WEB_ROOT, '', $dirs[sizeof($dirs) - 1]);
+$currentManual = Manual::GetLatestVersion();
 
 $url = HttpInput::GetString('url', true, '');
 $url = preg_replace('|^/|ius', '', $url);
@@ -21,4 +18,4 @@ if($url != ''){
 }
 
 http_response_code(302);
-header('Location: ' . $currentManual . $url);
+header('Location: /manual/' . $currentManual . $url);