diff --git a/.editorconfig b/.editorconfig
index 63f7b7b..9c546e0 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -24,3 +24,6 @@ indent_size = 2
 
 [/version.txt]
 insert_final_newline = false
+
+[*.yml]
+indent_style = space
diff --git a/docker/dev/mtt-php54-apache/Dockerfile b/docker/dev/mtt-php54-apache/Dockerfile
new file mode 100644
index 0000000..492964f
--- /dev/null
+++ b/docker/dev/mtt-php54-apache/Dockerfile
@@ -0,0 +1,4 @@
+
+FROM php:5.4-apache
+
+RUN docker-php-ext-install mysqli
diff --git a/docker/dev/mtt-php54-apache/docker-compose.yml b/docker/dev/mtt-php54-apache/docker-compose.yml
new file mode 100644
index 0000000..0da4917
--- /dev/null
+++ b/docker/dev/mtt-php54-apache/docker-compose.yml
@@ -0,0 +1,11 @@
+version: '3'
+services:
+  web:
+    build: ./
+    image: mtt-php5.4-apache
+    container_name: mtt-php54-apache
+    ports:
+    - "8080:80"
+    volumes:
+    - ../../src:/var/www/html
+    - ./php-mtt.ini:/usr/local/etc/php/conf.d/php-mtt.ini
diff --git a/docker/dev/mtt-php54-apache/php-mtt.ini b/docker/dev/mtt-php54-apache/php-mtt.ini
new file mode 100644
index 0000000..1bb6e2b
--- /dev/null
+++ b/docker/dev/mtt-php54-apache/php-mtt.ini
@@ -0,0 +1,6 @@
+
+# Since PHP 5.4 E_STRICT is included in E_ALL
+error_reporting = E_ALL
+
+#log_errors = On
+#display_errors = On
diff --git a/src/includes/class.db.sqlite3.php b/src/includes/class.db.sqlite3.php
index 950e65d..5cc47bb 100644
--- a/src/includes/class.db.sqlite3.php
+++ b/src/includes/class.db.sqlite3.php
@@ -152,10 +152,15 @@ class Database_Sqlite3
 
 	function table_exists($table)
 	{
-		$table = $this->dbh->quote($table);
-		$q = $this->dbh->query("SELECT 1 FROM $table WHERE 1=0");
-		if($q === false) return false;
-		else return true;
+		$exists = $this->sq("SELECT 1 FROM sqlite_master WHERE type='table' AND name=?", $table);
+		if ($exists == "1") {
+		  return true;
+		}
+		$exists = $this->sq("SELECT 1 FROM sqlite_temp_master WHERE type='table' AND name=?", $table);
+		if ($exists == "1") {
+		  return true;
+		}
+		return false;
 	}
 }
 
diff --git a/src/includes/common.php b/src/includes/common.php
index 475d997..9425ee2 100644
--- a/src/includes/common.php
+++ b/src/includes/common.php
@@ -164,14 +164,14 @@ class Config
 		if($f === false) throw new Exception("Error while saving config file");
 		fwrite($f, "<?php\n\$config = array();\n$s?>");
 		fclose($f);
-/*
+
 		//Reset Zend OPcache
 		//opcache_get_status() sometimes crashes
 		//TODO: save config in database!
 		if (function_exists("opcache_invalidate") && 0 != (int)opcache_get_configuration()["directives"]["opcache.enable"]) {
 			opcache_invalidate(MTTPATH. 'db/config.php', true);
 		}
- */
+
 	}
 }
 
diff --git a/src/setup.php b/src/setup.php
index ef33098..a3c1b04 100644
--- a/src/setup.php
+++ b/src/setup.php
@@ -336,6 +336,9 @@ function testConnect(&$error)
 	{
 		if(Config::get('db') == 'mysql')
 		{
+			if ( !function_exists("mysqli_connect") ) {
+				throw new Exception("Required PHP extension 'mysqli' is not installed");
+			}
 			require_once(MTTINC. 'class.db.mysql.php');
 			$db = new Database_Mysql;
 			$db->connect(Config::get('mysql.host'), Config::get('mysql.user'), Config::get('mysql.password'), Config::get('mysql.db'));