diff --git a/src/Module/Install.php b/src/Module/Install.php
index d1e2677585..bfb988cac3 100644
--- a/src/Module/Install.php
+++ b/src/Module/Install.php
@@ -43,6 +43,10 @@ class Install extends BaseModule
 	{
 		$a = self::getApp();
 
+		if (!$a->getMode()->isInstall()) {
+			Core\System::httpExit(403);
+		}
+
 		// route: install/testrwrite
 		// $baseurl/install/testrwrite to test if rewrite in .htaccess is working
 		if ($a->getArgumentValue(1, '') == 'testrewrite') {
@@ -62,6 +66,10 @@ class Install extends BaseModule
 	{
 		$a = self::getApp();
 
+		if (!$a->getMode()->isInstall()) {
+			Core\System::httpExit(403);
+		}
+
 		switch (self::$currentWizardStep) {
 			case self::SYSTEM_CHECK:
 			case self::DATABASE_CONFIG:
@@ -113,6 +121,10 @@ class Install extends BaseModule
 	{
 		$a = self::getApp();
 
+		if (!$a->getMode()->isInstall()) {
+			Core\System::httpExit(403);
+		}
+
 		$output = '';
 
 		$install_title = L10n::t('Friendica Communications Server - Setup');