diff --git a/src/_h5ai/server/php/inc/core/class-app.php b/src/_h5ai/server/php/inc/core/class-app.php
index e007fc1f..d5166539 100644
--- a/src/_h5ai/server/php/inc/core/class-app.php
+++ b/src/_h5ai/server/php/inc/core/class-app.php
@@ -10,7 +10,7 @@ class App {
 
         $this->request = $request;
         $this->setup = $setup;
-        $this->options = Util::load_commented_json($this->setup->get("APP_PATH") . "/conf/options.json");
+        $this->options = Util::load_commented_json($this->setup->get('APP_PATH') . '/conf/options.json');
     }
 
     public function get_request() {
@@ -28,28 +28,28 @@ class App {
         return $this->options;
     }
 
-    public function query_option($keypath = "", $default = null) {
+    public function query_option($keypath = '', $default = null) {
 
         return Util::array_query($this->options, $keypath, $default);
     }
 
     public function get_types() {
 
-        return Util::load_commented_json($this->setup->get("APP_PATH") . "/conf/types.json");
+        return Util::load_commented_json($this->setup->get('APP_PATH') . '/conf/types.json');
     }
 
     public function login_admin($pass) {
 
-        $key = $this->setup->get("AS_ADMIN_SESSION_KEY");
-        $hash = $this->setup->get("PASSHASH");
+        $key = $this->setup->get('AS_ADMIN_SESSION_KEY');
+        $hash = $this->setup->get('PASSHASH');
 
-        $_SESSION[$key] = strcasecmp(hash("sha512", $pass), $hash) === 0;
+        $_SESSION[$key] = strcasecmp(hash('sha512', $pass), $hash) === 0;
         return $_SESSION[$key];
     }
 
     public function logout_admin() {
 
-        $key = $this->setup->get("AS_ADMIN_SESSION_KEY");
+        $key = $this->setup->get('AS_ADMIN_SESSION_KEY');
 
         $_SESSION[$key] = false;
         return $_SESSION[$key];
@@ -57,32 +57,32 @@ class App {
 
     public function to_href($path, $trailing_slash = true) {
 
-        $rel_path = substr($path, strlen($this->setup->get("ROOT_PATH")));
-        $parts = explode("/", $rel_path);
+        $rel_path = substr($path, strlen($this->setup->get('ROOT_PATH')));
+        $parts = explode('/', $rel_path);
         $encoded_parts = [];
         foreach ($parts as $part) {
-            if ($part != "") {
+            if ($part != '') {
                 $encoded_parts[] = rawurlencode($part);
             }
         }
 
-        return Util::normalize_path($this->setup->get("ROOT_HREF") . implode("/", $encoded_parts), $trailing_slash);
+        return Util::normalize_path($this->setup->get('ROOT_HREF') . implode('/', $encoded_parts), $trailing_slash);
     }
 
     public function to_path($href) {
 
-        $rel_href = substr($href, strlen($this->setup->get("ROOT_HREF")));
-        return Util::normalize_path($this->setup->get("ROOT_PATH") . "/" . rawurldecode($rel_href));
+        $rel_href = substr($href, strlen($this->setup->get('ROOT_HREF')));
+        return Util::normalize_path($this->setup->get('ROOT_PATH') . '/' . rawurldecode($rel_href));
     }
 
     public function is_hidden($name) {
 
         // always hide
-        if ($name === "." || $name === "..") {
+        if ($name === '.' || $name === '..') {
             return true;
         }
 
-        foreach ($this->query_option("view.hidden", []) as $re) {
+        foreach ($this->query_option('view.hidden', []) as $re) {
             $re = Util::wrap_pattern($re);
             if (preg_match($re, $name)) {
                 return true;
@@ -100,7 +100,7 @@ class App {
                 if (
                     $this->is_hidden($name)
                     || $this->is_hidden($this->to_href($path) . $name)
-                    || (!is_readable($path .'/'. $name) && $this->query_option("view.hideIf403", false))
+                    || (!is_readable($path . '/' . $name) && $this->query_option('view.hideIf403', false))
                 ) {
                     continue;
                 }
@@ -121,18 +121,18 @@ class App {
             return false;
         }
 
-        if ($path === $this->setup->get("APP_PATH") || strpos($path, $this->setup->get("APP_PATH") . '/') === 0) {
+        if ($path === $this->setup->get('APP_PATH') || strpos($path, $this->setup->get('APP_PATH') . '/') === 0) {
             return false;
         }
 
-        foreach ($this->query_option("view.unmanaged", []) as $name) {
-            if (file_exists($path . "/" . $name)) {
+        foreach ($this->query_option('view.unmanaged', []) as $name) {
+            if (file_exists($path . '/' . $name)) {
                 return false;
             }
         }
 
-        while ($path !== $this->setup->get("ROOT_PATH")) {
-            if (@is_dir($path . "/_h5ai/server")) {
+        while ($path !== $this->setup->get('ROOT_PATH')) {
+            if (@is_dir($path . '/_h5ai/server')) {
                 return false;
             }
             $parent_path = Util::normalize_path(dirname($path));
@@ -167,7 +167,7 @@ class App {
             $folder = $folder->get_parent($cache);
         }
 
-        uasort($cache, ["Item", "cmp"]);
+        uasort($cache, ['Item', 'cmp']);
         $result = [];
         foreach ($cache as $p => $item) {
             $result[] = $item->to_json_object();
@@ -179,13 +179,13 @@ class App {
     public function get_langs() {
 
         $langs = [];
-        $l10n_path = $this->setup->get("APP_PATH") . "/conf/l10n";
+        $l10n_path = $this->setup->get('APP_PATH') . '/conf/l10n';
         if (is_dir($l10n_path)) {
             if ($dir = opendir($l10n_path)) {
                 while (($file = readdir($dir)) !== false) {
-                    if (Util::ends_with($file, ".json")) {
-                        $translations = Util::load_commented_json($l10n_path . "/" . $file);
-                        $langs[basename($file, ".json")] = $translations["lang"];
+                    if (Util::ends_with($file, '.json')) {
+                        $translations = Util::load_commented_json($l10n_path . '/' . $file);
+                        $langs[basename($file, '.json')] = $translations['lang'];
                     }
                 }
                 closedir($dir);
@@ -200,9 +200,9 @@ class App {
         $results = [];
 
         foreach ($iso_codes as $iso_code) {
-            $file = $this->setup->get("APP_PATH") . "/conf/l10n/" . $iso_code . ".json";
+            $file = $this->setup->get('APP_PATH') . '/conf/l10n/' . $iso_code . '.json';
             $results[$iso_code] = Util::load_commented_json($file);
-            $results[$iso_code]["isoCode"] = $iso_code;
+            $results[$iso_code]['isoCode'] = $iso_code;
         }
 
         return $results;
@@ -214,7 +214,7 @@ class App {
 
         foreach ($requests as $req) {
             $thumb = new Thumb($this);
-            $hrefs[] = $thumb->thumb($req["type"], $req["href"], $req["width"], $req["height"]);
+            $hrefs[] = $thumb->thumb($req['type'], $req['href'], $req['width'], $req['height']);
         }
 
         return $hrefs;
diff --git a/src/_h5ai/server/php/inc/core/class-fallback.php b/src/_h5ai/server/php/inc/core/class-fallback.php
index cdd30355..d59924eb 100644
--- a/src/_h5ai/server/php/inc/core/class-fallback.php
+++ b/src/_h5ai/server/php/inc/core/class-fallback.php
@@ -9,8 +9,8 @@ class Fallback {
 
     private function get_current_path() {
 
-        $uri_parts = parse_url(getenv("REQUEST_URI"));
-        $current_href = Util::normalize_path($uri_parts["path"], true);
+        $uri_parts = parse_url(getenv('REQUEST_URI'));
+        $current_href = Util::normalize_path($uri_parts['path'], true);
         $current_path = $this->app->to_path($current_href);
 
         if (!is_dir($current_path)) {
@@ -26,12 +26,12 @@ class Fallback {
             $path = $this->get_current_path();
         }
 
-        $app_href = $this->app->get_setup()->get("APP_HREF");
+        $app_href = $this->app->get_setup()->get('APP_HREF');
 
         $cache = [];
         $folder = Item::get($this->app, $path, $cache);
         $items = $folder->get_content($cache);
-        uasort($items, ["Item", "cmp"]);
+        uasort($items, ['Item', 'cmp']);
 
         $html = "<table>";
 
@@ -52,13 +52,13 @@ class Fallback {
         }
 
         foreach ($items as $item) {
-            $type = $item->is_folder ? "folder" : "file";
+            $type = $item->is_folder ? 'folder' : 'file';
 
             $html .= "<tr>";
             $html .= "<td class='fb-i'><img src='${app_href}client/images/fallback/${type}.png' alt='${type}'/></td>";
             $html .= "<td class='fb-n'><a href='" . $item->href . "'>" . basename($item->path) . "</a></td>";
-            $html .= "<td class='fb-d'>" . date("Y-m-d H:i", $item->date) . "</td>";
-            $html .= "<td class='fb-s'>" . ($item->size !== null ? intval($item->size / 1000) . " KB" : "" ) . "</td>";
+            $html .= "<td class='fb-d'>" . date('Y-m-d H:i', $item->date) . "</td>";
+            $html .= "<td class='fb-s'>" . ($item->size !== null ? intval($item->size / 1000) . ' KB' : '' ) . "</td>";
             $html .= "</tr>";
         }
 
diff --git a/src/_h5ai/server/php/inc/core/class-item.php b/src/_h5ai/server/php/inc/core/class-item.php
index b1d87963..25eca2f8 100644
--- a/src/_h5ai/server/php/inc/core/class-item.php
+++ b/src/_h5ai/server/php/inc/core/class-item.php
@@ -17,7 +17,7 @@ class Item {
 
     public static function get($app, $path, &$cache) {
 
-        if (!Util::starts_with($path, $app->get_setup()->get("ROOT_PATH"))) {
+        if (!Util::starts_with($path, $app->get_setup()->get('ROOT_PATH'))) {
             return null;
         }
 
@@ -55,14 +55,14 @@ class Item {
     public function to_json_object() {
 
         $obj = [
-            "href" => $this->href,
-            "time" => $this->date * 1000, // seconds (PHP) to milliseconds (JavaScript)
-            "size" => $this->size
+            'href' => $this->href,
+            'time' => $this->date * 1000, // seconds (PHP) to milliseconds (JavaScript)
+            'size' => $this->size
         ];
 
         if ($this->is_folder) {
-            $obj["managed"] = $this->app->is_managed_href($this->href);
-            $obj["fetched"] = $this->is_content_fetched;
+            $obj['managed'] = $this->app->is_managed_href($this->href);
+            $obj['fetched'] = $this->is_content_fetched;
         }
 
         return $obj;
@@ -72,7 +72,7 @@ class Item {
     public function get_parent(&$cache) {
 
         $parent_path = Util::normalize_path(dirname($this->path), false);
-        if ($parent_path !== $this->path && Util::starts_with($parent_path, $this->app->get_setup()->get("ROOT_PATH"))) {
+        if ($parent_path !== $this->path && Util::starts_with($parent_path, $this->app->get_setup()->get('ROOT_PATH'))) {
             return Item::get($this->app, $parent_path, $cache);
         }
         return null;
@@ -89,7 +89,7 @@ class Item {
 
         $files = $this->app->read_dir($this->path);
         foreach ($files as $file) {
-            $item = Item::get($this->app, $this->path . "/" . $file, $cache);
+            $item = Item::get($this->app, $this->path . '/' . $file, $cache);
             $items[$item->path] = $item;
         }
 
diff --git a/src/_h5ai/server/php/inc/core/class-logger.php b/src/_h5ai/server/php/inc/core/class-logger.php
index bbf8e1d6..062aacd3 100644
--- a/src/_h5ai/server/php/inc/core/class-logger.php
+++ b/src/_h5ai/server/php/inc/core/class-logger.php
@@ -9,8 +9,8 @@ class Logger {
 
         self::$start = self::time();
         self::$prev = self::$start;
-        register_shutdown_function(function () { Logger::log("shutdown"); });
-        Logger::log("--------------------------------");
+        register_shutdown_function(function () { Logger::log('shutdown'); });
+        Logger::log('--------------------------------');
     }
 
     private static function time() {
@@ -21,9 +21,9 @@ class Logger {
     public static function log($message=null, $obj=null) {
 
         $now = self::time();
-        $message = number_format($now - self::$start, 3) . " " . number_format($now - self::$prev, 3) . " " . $message;
+        $message = number_format($now - self::$start, 3) . ' ' . number_format($now - self::$prev, 3) . ' ' . $message;
 
-        @error_log($message . " " . var_export($obj, true));
+        @error_log($message . ' ' . var_export($obj, true));
 
         self::$prev = $now;
     }
diff --git a/src/_h5ai/server/php/inc/core/class-request.php b/src/_h5ai/server/php/inc/core/class-request.php
index ba5cae9b..d8d74f7f 100644
--- a/src/_h5ai/server/php/inc/core/class-request.php
+++ b/src/_h5ai/server/php/inc/core/class-request.php
@@ -9,35 +9,35 @@ class Request {
         $this->params = $params;
     }
 
-    public function query($keypath = "", $default = Util::NO_DEFAULT) {
+    public function query($keypath = '', $default = Util::NO_DEFAULT) {
 
         $value = Util::array_query($this->params, $keypath, Util::NO_DEFAULT);
 
         if ($value === Util::NO_DEFAULT) {
-            Util::json_fail(Util::ERR_MISSING_PARAM, "parameter '$keypath' is missing", $default === Util::NO_DEFAULT);
+            Util::json_fail(Util::ERR_MISSING_PARAM, 'parameter \'' . $keypath . '\' is missing', $default === Util::NO_DEFAULT);
             return $default;
         }
 
         return $value;
     }
 
-    public function query_boolean($keypath = "", $default = Util::NO_DEFAULT) {
+    public function query_boolean($keypath = '', $default = Util::NO_DEFAULT) {
 
         $value = $this->query($keypath, $default);
         return filter_var($value, FILTER_VALIDATE_BOOLEAN);
     }
 
-    public function query_numeric($keypath = "", $default = Util::NO_DEFAULT) {
+    public function query_numeric($keypath = '', $default = Util::NO_DEFAULT) {
 
         $value = $this->query($keypath, $default);
-        Util::json_fail(Util::ERR_ILLIGAL_PARAM, "parameter '$keypath' is not numeric", !is_numeric($value));
+        Util::json_fail(Util::ERR_ILLIGAL_PARAM, 'parameter \'' . $keypath . '\' is not numeric', !is_numeric($value));
         return intval($value, 10);
     }
 
-    public function query_array($keypath = "", $default = Util::NO_DEFAULT) {
+    public function query_array($keypath = '', $default = Util::NO_DEFAULT) {
 
         $value = $this->query($keypath, $default);
-        Util::json_fail(Util::ERR_ILLIGAL_PARAM, "parameter '$keypath' is no array", !is_array($value));
+        Util::json_fail(Util::ERR_ILLIGAL_PARAM, 'parameter \'' . $keypath . '\' is no array', !is_array($value));
         return $value;
     }
 }