diff --git a/cron.php b/cron.php
index ad6dd77..467b11d 100644
--- a/cron.php
+++ b/cron.php
@@ -14,9 +14,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("config.php");
-require_once("mail_templates.php");
-require_once("database.php");
+require_once(__DIR__ . "/config.php");
+require_once(__DIR__ . "/mail_templates.php");
+require_once(__DIR__ . "/database.php");
 
 $sql = "SELECT id, first_name, last_name, username, email, state, note, verify_token, admin_token FROM registrations "
         . "WHERE state = " . RegisterState::PendingEmailSend
@@ -46,7 +46,7 @@ foreach ($mx_db->query($sql) as $row) {
                 }
                 break;
             case RegisterState::PendingAdminSend:
-                require_once("MatrixConnection.php");
+                require_once(__DIR__ . "/MatrixConnection.php");
                 $adminUrl = $config["webroot"] . "/verify_admin.php?t=" . $row["admin_token"];
                 $mxConn = new MatrixConnection($config["homeserver"], $config["access_token"]);
                 $mxMsg = new MatrixMessage();
diff --git a/database.php b/database.php
index fef634c..6c0c689 100644
--- a/database.php
+++ b/database.php
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("config.php");
+require_once(__DIR__ . "/config.php");
 if (!isset($config["databaseURI"])) {
     throw new Exception("malformed configuration: databaseURI not defined");
 }
diff --git a/internal/directory_search.php b/internal/directory_search.php
index 2149a82..2620b32 100644
--- a/internal/directory_search.php
+++ b/internal/directory_search.php
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("../database.php");
+require_once(__DIR__ . "/../database.php");
 $response = [
     "limited" => false,
     "result" => [],
diff --git a/internal/identity_bulk.php b/internal/identity_bulk.php
index 8c87e12..0255528 100644
--- a/internal/identity_bulk.php
+++ b/internal/identity_bulk.php
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("../database.php");
+require_once(__DIR__ . "/../database.php");
 $response = [
     "lookup" => []
 ];
diff --git a/internal/identity_single.php b/internal/identity_single.php
index fde3dd8..96c816a 100644
--- a/internal/identity_single.php
+++ b/internal/identity_single.php
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("../database.php");
+require_once(__DIR__ . "/../database.php");
 $response = new stdClass;
 try {
     $inputJSON = file_get_contents('php://input');
diff --git a/internal/intercept_change_password.php b/internal/intercept_change_password.php
index 4b937e4..0d03811 100644
--- a/internal/intercept_change_password.php
+++ b/internal/intercept_change_password.php
@@ -44,14 +44,14 @@ try {
         throw new Exception('"new_password" is not defined');
     }
 
-    require_once("../helpers.php");
+    require_once(__DIR__ . "/../helpers.php");
     $localpart = stripLocalpart($input["auth"]["user"]);
 
     if (empty($localpart)) {
         throw new Exception("localpart cannot be identified");
     }
 
-    require_once("../database.php");
+    require_once(__DIR__ . "/../database.php");
     if (!$mx_db->updatePassword(
                     $localpart, $input["auth"]["password"], $input["new_password"]
             )) {
diff --git a/internal/login.php b/internal/login.php
index 9f44dbe..72380ea 100644
--- a/internal/login.php
+++ b/internal/login.php
@@ -20,7 +20,7 @@ $response = [
     ]
 ];
 
-require_once("../database.php");
+require_once(__DIR__ . "/../database.php");
 
 abstract class LoginRequester {
 
@@ -56,7 +56,7 @@ try {
     // prefer the localpart attribute of mxisd. But in case of matrix-synapse-rest-auth
     // we have to parse it on our own
     if (empty($localpart)) {
-        require_once("../helpers.php");
+        require_once(__DIR__ . "/../helpers.php");
         $localpart = stripLocalpart($mxid);
     }
 
diff --git a/lang/mail.de-de.php b/lang/mail.de-de.php
index 3201f39..42eaaec 100644
--- a/lang/mail.de-de.php
+++ b/lang/mail.de-de.php
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 function send_mail($receiver, $subject, $body) {
-	include("../config.php");
+	include(__DIR__ . "/../config.php");
 	$headers = "From: " . $config["register_email"] . "\r\n"
 		. "Content-Type: text/plain;charset=utf-8";
 	return mail($receiver, $subject, $body, $headers);
diff --git a/lang/mail.en-gb.php b/lang/mail.en-gb.php
index f156b7c..b77a285 100644
--- a/lang/mail.en-gb.php
+++ b/lang/mail.en-gb.php
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 function send_mail($receiver, $subject, $body) {
-	include("../config.php");
+	include(__DIR__ . "/../config.php");
 	$headers = "From: " . $config["register_email"] . "\r\n"
 		. "Content-Type: text/plain;charset=utf-8";
 	return mail($receiver, $subject, $body, $headers);
diff --git a/language.php b/language.php
index 14fe117..f927350 100644
--- a/language.php
+++ b/language.php
@@ -14,7 +14,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("config.php");
+require_once(__DIR__ . "/config.php");
 $lang = $config["defaultLanguage"];
 
 if (isset($_GET['lang'])) {
@@ -25,7 +25,7 @@ if (!file_exists($lang_file)) {
     error_log("Translation for " . $lang . " not found. Fallback to 'de-de'");
     $lang = "de-de";
 }
-$lang_file = dirname(__FILE__) . "/lang/lang." . $lang . ".php";
+$lang_file = __DIR__ . "/lang/lang." . $lang . ".php";
 require_once($lang_file);
 unset($lang_file);
 ?>
diff --git a/mail_templates.php b/mail_templates.php
index 3d62e3c..3383ea0 100644
--- a/mail_templates.php
+++ b/mail_templates.php
@@ -14,17 +14,17 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once("config.php");
+require_once(__DIR__ . "/config.php");
 $lang = $config["defaultLanguage"];
 if (isset($_GET['lang'])) {
     $lang = filter_var($_GET['lang'], FILTER_SANITIZE_STRING);
 }
-$lang_file = dirname(__FILE__) . "/lang/mail." . $lang . ".php";
+$lang_file = __DIR__ . "/lang/mail." . $lang . ".php";
 if (!file_exists($lang_file)) {
     error_log("Mail templates for '" . $lang . "' not found. Fallback to 'de-de'");
     $lang = "de-de";
 }
-$lang_file = dirname(__FILE__) . "/lang/mail." . $lang . ".php";
+$lang_file = __DIR__ . "/lang/mail." . $lang . ".php";
 require_once($lang_file);
 unset($lang_file);
 ?>
diff --git a/public/index.php b/public/index.php
index df9db26..32b5d5d 100644
--- a/public/index.php
+++ b/public/index.php
@@ -19,12 +19,12 @@ if (!isset($_SERVER['HTTPS'])) {
     exit();
 }
 
-require_once "../language.php";
+require_once(__DIR__ . "/../language.php");
 if (!file_exists("../config.php")) {
     print($language["NO_CONFIGURATION"]);
     exit();
 }
-require_once "../config.php";
+require_once(__DIR__ . "/../config.php");
 
 // this values will not be used when using the register operation type
 $storeFirstLastName = false;
@@ -86,7 +86,7 @@ if ($_SERVER["REQUEST_METHOD"] == "POST") {
         $note = filter_var($_POST["note"], FILTER_SANITIZE_STRING);
         $email = filter_var($_POST["email"], FILTER_VALIDATE_EMAIL);
 
-        require_once("../database.php");
+        require_once(__DIR__ . "/../database.php");
         $res = $mx_db->addRegistration($first_name, $last_name, $username, $note, $email);
 
         if (!isset($res["verify_token"])) {
@@ -96,7 +96,7 @@ if ($_SERVER["REQUEST_METHOD"] == "POST") {
         $verify_token = $res["verify_token"];
 
         $verify_url = $config["webroot"] . "/verify.php?t=" . $verify_token;
-        require_once "../mail_templates.php";
+        require_once(__DIR__ . "/../mail_templates.php");
         $success = send_mail_pending_verification(
                 $config["homeserver"], $storeFirstLastName ? $first_name . " " . $last_name : $username, $email, $verify_url);
 
@@ -246,4 +246,4 @@ if ($_SERVER["REQUEST_METHOD"] == "POST") {
 <?php } ?>
     </script>
 <?php } ?>
-</body></html>
\ No newline at end of file
+</body></html>
diff --git a/public/verify.php b/public/verify.php
index 35b9af0..a383b97 100644
--- a/public/verify.php
+++ b/public/verify.php
@@ -13,13 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once "../language.php";
+require_once(__DIR__ . "/../language.php");
 if (!file_exists("../config.php")) {
     print($language["NO_CONFIGURATION"]);
     exit();
 }
-require_once "../config.php";
-require_once "../mail_templates.php";
+require_once(__DIR__ . "/../config.php");
+require_once(__DIR__ . "/../mail_templates.php");
 
 // enforce admin via https
 if (!isset($_SERVER['HTTPS'])) {
@@ -38,7 +38,7 @@ try {
     }
     $token = filter_var($_GET["t"], FILTER_SANITIZE_STRING);
 
-    require_once("../database.php");
+    require_once(__DIR__ . "/../database.php");
 
     $user = $mx_db->getUserForVerify($token);
     if ($user == NULL) {
@@ -51,7 +51,7 @@ try {
     $email = $user["email"];
     $admin_token = $user["admin_token"];
 
-    require_once("../MatrixConnection.php");
+    require_once(__DIR__ . "/../MatrixConnection.php");
     $adminUrl = $config["webroot"] . "/verify_admin.php?t=" . $admin_token;
     $mxConn = new MatrixConnection($config["homeserver"], $config["access_token"]);
     $mxMsg = new MatrixMessage();
diff --git a/public/verify_admin.php b/public/verify_admin.php
index 9e98375..0b7a890 100644
--- a/public/verify_admin.php
+++ b/public/verify_admin.php
@@ -13,13 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-require_once "../language.php";
+require_once(__DIR__ . "/../language.php");
 if (!file_exists("../config.php")) {
     print($language["NO_CONFIGURATION"]);
     exit();
 }
-require_once "../config.php";
-require_once "../mail_templates.php";
+require_once(__DIR__ . "/../config.php");
+require_once(__DIR__ . "/../mail_templates.php");
 
 // enforce admin via https
 if (!isset($_SERVER['HTTPS'])) {
@@ -38,7 +38,7 @@ try {
     }
     $token = filter_var($_GET["t"], FILTER_SANITIZE_STRING);
 
-    require_once("../database.php");
+    require_once(__DIR__ . "/../database.php");
 
     $action = NULL;
     if (isset($_GET["allow"])) {
@@ -67,7 +67,7 @@ try {
         $mx_db->setRegistrationStateAdmin(RegisterState::PendingRegistration, $token);
 
         // register user
-        require_once("../MatrixConnection.php");
+        require_once(__DIR__ . "/../MatrixConnection.php");
         $mxConn = new MatrixConnection($config["homeserver"], $config["access_token"]);
 
         $password = NULL;
@@ -205,5 +205,5 @@ try {
         print("<a href=\"" . $config["webroot"] . "/index.php" . "\">" . $language["JUMP_TO_HOMEPAGE"] . "</a>");
     }
     ?>
-                    < /body>
-         </html>
+    </body>
+</html>