diff --git a/lib/Ebook.php b/lib/Ebook.php
index a4137232..3fb36043 100644
--- a/lib/Ebook.php
+++ b/lib/Ebook.php
@@ -209,7 +209,7 @@ class Ebook{
 			$this->TocEntries = [];
 			$tocDom = new SimpleXMLElement(str_replace('xmlns=', 'ns=', file_get_contents($wwwFilesystemPath . '/toc.xhtml') ?: ''));
 			$tocDom->registerXPathNamespace('epub', 'http://www.idpf.org/2007/ops');
-			foreach($tocDom->xpath('/html/body//nav[@epub:type="toc"]//a[not(contains(@epub:type, "z3998:roman")) and not(text() = "Titlepage" or text() = "Imprint" or text() = "Colophon" or text() = "Endnotes" or text() = "Uncopyright") and not(contains(@href, "halftitle"))]') as $item){
+			foreach($tocDom->xpath('/html/body//nav[@epub:type="toc"]//a[not(contains(@epub:type, "z3998:roman")) and not(text() = "Titlepage" or text() = "Imprint" or text() = "Colophon" or text() = "Endnotes" or text() = "Uncopyright") and not(contains(@href, "halftitle"))]') ?: [] as $item){
 				$this->TocEntries[] = (string)$item;
 			}
 		}
diff --git a/lib/HttpInput.php b/lib/HttpInput.php
index 2755426c..bd96d6e8 100644
--- a/lib/HttpInput.php
+++ b/lib/HttpInput.php
@@ -26,6 +26,9 @@ class HttpInput{
 		return self::GetHttpVar($variable, HTTP_VAR_DEC, GET, $default);
 	}
 
+	/**
+	 * @return array<string>
+	 */
 	public static function GetArray(string $variable, array $default = null): ?array{
 		return self::GetHttpVar($variable, HTTP_VAR_ARRAY, GET, $default);
 	}
diff --git a/lib/Library.php b/lib/Library.php
index b64fe1f8..781fb8d8 100644
--- a/lib/Library.php
+++ b/lib/Library.php
@@ -1,6 +1,7 @@
 <?
 use function Safe\apcu_fetch;
 use function Safe\ksort;
+use function Safe\natsort;
 use function Safe\preg_replace;
 use function Safe\touch;
 use function Safe\unlink;
@@ -10,7 +11,7 @@ class Library{
 	/**
 	 * @return array<Ebook>
 	 */
-	public static function FilterEbooks($query = null, $tags = [], $sort = null){
+	public static function FilterEbooks(string $query = null, array $tags = [], string $sort = null){
 		$ebooks = Library::GetEbooks();
 		$matches = $ebooks;
 
@@ -164,6 +165,10 @@ class Library{
 		return $ebooks;
 	}
 
+
+	/**
+	 * @return array<Tag>
+	 */
 	public static function GetTags(): array{
 		return apcu_fetch('tags');
 	}
diff --git a/lib/Manual.php b/lib/Manual.php
index a7676f4a..439bed0b 100644
--- a/lib/Manual.php
+++ b/lib/Manual.php
@@ -1,13 +1,16 @@
 <?
+use function Safe\glob;
+use function Safe\preg_match_all;
+use function Safe\sort;
 
 class Manual{
-	public static function GetLatestVersion(){
+	public static function GetLatestVersion(): string{
 		$dirs = glob(MANUAL_PATH . '/*', GLOB_ONLYDIR);
 		sort($dirs);
 		return str_replace(MANUAL_PATH . '/', '', $dirs[sizeof($dirs) - 1]);
 	}
 
-	public static function GetRequestedVersion(){
+	public static function GetRequestedVersion(): ?string{
 		try{
 			if(preg_match_all('|/manual/([0-9]+\.[0-9]+\.[0-9]+)|ius', $_SERVER['REQUEST_URI'], $matches)){
 				return($matches[1][0]);
diff --git a/scripts/generate-opds.php b/scripts/generate-opds.php
index 52d4f1df..84d86087 100644
--- a/scripts/generate-opds.php
+++ b/scripts/generate-opds.php
@@ -22,6 +22,8 @@ foreach($contentFiles as $path){
 	if($path == '')
 		continue;
 
+	$ebookWwwFilesystemPath = '';
+
 	try{
 		$ebookWwwFilesystemPath = preg_replace('|/content\.opf|ius', '', $path) ?? '';
 
diff --git a/www/ebooks/index.php b/www/ebooks/index.php
index dc08de10..b52f84c9 100644
--- a/www/ebooks/index.php
+++ b/www/ebooks/index.php
@@ -9,7 +9,7 @@ try{
 	$query = HttpInput::GetString('query', false);
 	$tags = HttpInput::GetArray('tags', []);
 	$collection = HttpInput::GetString('collection', false);
-	$view = Httpinput::GetString('view', false);
+	$view = HttpInput::GetString('view', false);
 	$sort = HttpInput::GetString('sort', false);
 	$pages = 0;
 	$totalEbooks = 0;
@@ -117,7 +117,7 @@ try{
 		}
 
 		if($perPage !== EBOOKS_PER_PAGE){
-			$queryString .= '&amp;per-page=' . urlencode($perPage);
+			$queryString .= '&amp;per-page=' . urlencode((string)$perPage);
 		}
 	}