diff --git a/src/WC/WooCommerceHandler.php b/src/WC/WooCommerceHandler.php
index 8dfa9d06fb05583e8f4885571722ae14a8f96640..890bf9304d5d245c349c252589aa60542b301ac9 100644
--- a/src/WC/WooCommerceHandler.php
+++ b/src/WC/WooCommerceHandler.php
@@ -23,7 +23,7 @@ class WooCommerceHandler extends AbstractProcessingHandler {
 	 * @param  array $record
 	 * @return void
 	 */
-	protected function write( array $record ) {
+	protected function write( array $record ): void {
 		$context = array_merge(
 			[
 				'source' => $this->channel,
@@ -39,7 +39,7 @@ class WooCommerceHandler extends AbstractProcessingHandler {
 	 * @param int $level
 	 * @return string
 	 */
-	private function convertMonologLevelToWC( $level ) {
+	private function convertMonologLevelToWC( $level ): string {
 		return Logger::getLevelName( $level );
 	}
 
diff --git a/src/WC/WooCommerceMonologPlugin.php b/src/WC/WooCommerceMonologPlugin.php
index b70669afeac759f181094adb400c962c96696f7a..9fe47c8573b6a3eaf8fc118876d48818c69b8497 100644
--- a/src/WC/WooCommerceMonologPlugin.php
+++ b/src/WC/WooCommerceMonologPlugin.php
@@ -32,7 +32,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @param string $source
      */
-    public function clear($source = '')
+    public function clear($source = ''): void
     {
         $this->originalWCLogger->clear($source);
     }
@@ -40,7 +40,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
     /**
      * Method added for compatibility with \WC_Logger
      */
-    public function clear_expired_logs()
+    public function clear_expired_logs(): void
     {
         $this->originalWCLogger->clear_expired_logs();
     }
@@ -55,7 +55,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @deprecated
      */
-    public function add($handle, $message, $level = WC_Log_Levels::NOTICE)
+    public function add($handle, $message, $level = WC_Log_Levels::NOTICE): void
     {
         $this->log($message, $level);
     }
@@ -68,12 +68,12 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function emergency($message, $context = array())
+    public function emergency($message, $context = array()): void
     {
         $this->log(LogLevel::EMERGENCY, $message, $context);
     }
 
-    public function log($level, $message, $context = [])
+    public function log($level, $message, $context = []): void
     {
         $this->monolog->log($level, $message, $context);
     }
@@ -89,7 +89,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function alert($message, $context = array())
+    public function alert($message, $context = array()): void
     {
         $this->log(LogLevel::ALERT, $message, $context);
     }
@@ -104,7 +104,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function critical($message, $context = array())
+    public function critical($message, $context = array()): void
     {
         $this->log(LogLevel::CRITICAL, $message, $context);
     }
@@ -118,7 +118,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function error($message, $context = array())
+    public function error($message, $context = array()): void
     {
         $this->log(LogLevel::ERROR, $message, $context);
     }
@@ -134,7 +134,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function warning($message, $context = array())
+    public function warning($message, $context = array()): void
     {
         $this->log(LogLevel::WARNING, $message, $context);
     }
@@ -147,7 +147,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function notice($message, $context = array())
+    public function notice($message, $context = array()): void
     {
         $this->log(LogLevel::NOTICE, $message, $context);
     }
@@ -162,7 +162,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function info($message, $context = array())
+    public function info($message, $context = array()): void
     {
         $this->log(LogLevel::INFO, $message, $context);
     }
@@ -175,7 +175,7 @@ class WooCommerceMonologPlugin implements \WC_Logger_Interface
      *
      * @return void
      */
-    public function debug($message, $context = array())
+    public function debug($message, $context = array()): void
     {
         $this->log(LogLevel::DEBUG, $message, $context);
     }