diff --git a/composer.json b/composer.json
index 6dd06e9..3fa6538 100644
--- a/composer.json
+++ b/composer.json
@@ -8,6 +8,9 @@
         "nilportugues/sql-query-formatter": "^1.2.2",
         "firephp/firephp-core": "^0.5.3"
     },
+    "require-dev": {
+        "phpstan/phpstan": "^1.10"
+    },
     "license": "GPL-3.0",
     "autoload": {
         "psr-4": {
@@ -27,5 +30,8 @@
             "email": "info@shopmodule.com",
             "homepage": "https://www.d3data.de"
         }
-    ]
+    ],
+    "scripts": {
+        "phpstan": "./vendor/bin/phpstan --configuration=vendor/d3/oxid-sql-logger/phpstan.neon analyse"
+    }
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..7c47f35
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,14 @@
+parameters:
+    scanFiles:
+        - ../../oxid-esales/oxideshop-ce/source/bootstrap.php
+        - ../../oxid-esales/oxideshop-ce/source/oxfunctions.php
+        - ../../oxid-esales/oxideshop-ce/source/overridablefunctions.php
+    paths:
+        - ./src
+        - ./example
+    level: 9
+    phpVersion: 80300
+    checkMissingIterableValueType: false
+    treatPhpDocTypesAsCertain: false
+    featureToggles:
+        disableRuntimeReflectionProvider: true
diff --git a/src/Extensions/d3FirePHP.php b/src/Extensions/d3FirePHP.php
index de7251d..79ea60d 100644
--- a/src/Extensions/d3FirePHP.php
+++ b/src/Extensions/d3FirePHP.php
@@ -68,7 +68,7 @@ class d3FirePHP extends FirePHP
      *
      * @see FirePHP::TRACE
      * @param string $label
-     * @return true
+     * @return bool
      * @throws Exception
      */
     public function trace($label): bool
diff --git a/src/LoggerFactory.php b/src/LoggerFactory.php
index 8cb8f4c..af192ec 100644
--- a/src/LoggerFactory.php
+++ b/src/LoggerFactory.php
@@ -10,16 +10,18 @@ declare(strict_types=1);
 namespace D3\OxidSqlLogger;
 
 use Monolog;
+use Monolog\Logger;
 use OxidEsales\Eshop\Core\Registry;
 use Symfony\Component\Console\Formatter\OutputFormatterStyle;
 
 class LoggerFactory
 {
     /**
-     * @param $name
-     * @return Monolog\Logger
+     * @param string $name
+     *
+     * @return Logger
      */
-    public function create($name): Monolog\Logger
+    public function create(string $name): Monolog\Logger
     {
         return new Monolog\Logger($name, $this->getHandlers(), $this->getProcessors());
     }
@@ -52,17 +54,17 @@ class LoggerFactory
     }
 
     /**
-     * @param array $classNames
+     * @param iterable $classNames
      *
      * @return array
      */
-    private function getInstancesFromHandlerList(array $classNames): array
+    private function getInstancesFromHandlerList(iterable $classNames): array
     {
         return array_map(
             function($className){
                 return new $className();
             },
-            $classNames
+            (array) $classNames
         );
     }
 
diff --git a/src/OxidEsalesDatabase.php b/src/OxidEsalesDatabase.php
index 5bd993b..acab1a3 100644
--- a/src/OxidEsalesDatabase.php
+++ b/src/OxidEsalesDatabase.php
@@ -13,6 +13,7 @@ use Doctrine\DBAL\Configuration;
 use Doctrine\DBAL\Logging\SQLLogger;
 use OxidEsales\Eshop\Core\Database\Adapter\Doctrine\Database;
 use OxidEsales\EshopCommunity\Internal\Container\ContainerFactory;
+use OxidEsales\EshopCommunity\Internal\Framework\Database\ConnectionProvider;
 use OxidEsales\EshopCommunity\Internal\Framework\Database\ConnectionProviderInterface;
 use Psr\Container\ContainerExceptionInterface;
 use Psr\Container\NotFoundExceptionInterface;
@@ -32,10 +33,10 @@ class OxidEsalesDatabase extends Database
 
         $this->d3GetConfiguration()->setSQLLogger(
             new OxidSQLLogger(
-                $trace[1]['file'] ?? null,
-                (int) $trace[1]['line'] ?? null,
-                $trace[2]['class'] ?? null,
-                $trace[2]['function'] ?? null,
+                $trace[1]['file'] ?? '',
+                array_key_exists('line', $trace[1]) ? (int) $trace[1]['line'] : 0,
+                $trace[2]['class'] ?? '',
+                $trace[2]['function'] ?? '',
                 $message
             )
         );
@@ -61,13 +62,15 @@ class OxidEsalesDatabase extends Database
     }
 
     /**
-     * @return Configuration|null
+     * @return Configuration
      * @throws ContainerExceptionInterface
      * @throws NotFoundExceptionInterface
      */
-    protected function d3GetConfiguration(): ?Configuration
+    protected function d3GetConfiguration(): Configuration
     {
-        return ContainerFactory::getInstance()->getContainer()
-                        ->get(ConnectionProviderInterface::class)->get()->getConfiguration();
+        /** @var ConnectionProvider $connectionProvider */
+        $connectionProvider = ContainerFactory::getInstance()->getContainer()
+                                              ->get(ConnectionProviderInterface::class);
+        return $connectionProvider->get()->getConfiguration();
     }
 }
diff --git a/src/OxidSQLLogger.php b/src/OxidSQLLogger.php
index c6c6b69..48a3a53 100644
--- a/src/OxidSQLLogger.php
+++ b/src/OxidSQLLogger.php
@@ -37,7 +37,7 @@ class OxidSQLLogger implements SQLLogger
             Monolog\Registry::addLogger((new LoggerFactory())->create('sql'));
         }
 
-        $this->message              = $message;
+        $this->message              = (string) $message;
         $this->logStartingFile      = $file;
         $this->logStartingLine      = $line;
         $this->logStartingClass     = $class;
@@ -92,6 +92,7 @@ class OxidSQLLogger implements SQLLogger
         if ($this->SQLQuery) {
             $formatter = new Formatter();
 
+            // @phpstan-ignore-next-line
             Monolog\Registry::sql()->addDebug(
                 '['.$this->SQLQuery->getReadableElapsedTime().'] ' . ($this->message ?: $this->SQLQuery->getSql()),
                 [
diff --git a/src/SQLQuery.php b/src/SQLQuery.php
index 5866612..2ae5207 100644
--- a/src/SQLQuery.php
+++ b/src/SQLQuery.php
@@ -53,7 +53,7 @@ class SQLQuery
 
     /**
      * @param string $sql
-     * @return SQLQuery
+     * @return static
      */
     public function setSql(string $sql): static
     {
@@ -72,7 +72,7 @@ class SQLQuery
     /**
      * @param array|null $params
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setParams(array $params = null): static
     {
@@ -91,7 +91,7 @@ class SQLQuery
     /**
      * @param array|null $types
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setTypes(array $types = null): static
     {
@@ -109,7 +109,7 @@ class SQLQuery
     
     /**
      * @param string $file
-     * @return SQLQuery
+     * @return static
      */
     public function setLogStartingFile(string $file): static
     {
@@ -125,7 +125,7 @@ class SQLQuery
     /**
      * @param int $line
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setLogStartingLine(int $line): static
     {
@@ -144,7 +144,7 @@ class SQLQuery
     /**
      * @param string $classname
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setLogStartingClass(string $classname): static
     {
@@ -163,7 +163,7 @@ class SQLQuery
     /**
      * @param string $functionname
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setLogStartingFunction(string $functionname): static
     {
@@ -174,7 +174,7 @@ class SQLQuery
     /**
      * Statement was cancelled prematurely, an error was thrown.
      *
-     * @return SQLQuery
+     * @return static
      */
     public function setCanceled(): static
     {
@@ -227,7 +227,7 @@ class SQLQuery
             $unit = 'ms';
             $time = round($microtime*1000);
 
-            $format = preg_replace('/(%.\d+f)/', '%d', $format);
+            $format = (string) preg_replace('/(%.\d+f)/', '%d', $format);
         }
 
         return sprintf($format, $time, $unit);
diff --git a/src/functions.php b/src/functions.php
index 9b72d4a..4483df4 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -36,15 +36,17 @@ function D3StopSQLLog(): void
 }
 
 /**
- * @param $message
+ * @param string $message
  *
  * @throws ContainerExceptionInterface
  * @throws NotFoundExceptionInterface
  */
-function D3AddSQLLogItem($message): void
+function D3AddSQLLogItem(string $message): void
 {
     /** @var OxidEsalesDatabase $database */
     $database = oxNew( OxidEsalesDatabase::class);
-    $database->d3GetLogger()->startQuery($message);
-    $database->d3GetLogger()->stopQuery();
+    if ($logger = $database->d3GetLogger()) {
+        $logger->startQuery( $message );
+        $logger->stopQuery();
+    }
 }