diff --git a/lib/SimpleSAML/Logger/ErrorLogLoggingHandler.php b/lib/SimpleSAML/Logger/ErrorLogLoggingHandler.php
index 5d5f6cafe4c3feb4551e5d944b35c95fa934a0bc..0fdbdeddfdb8a6ccaba230f9e7a214c24b9459c9 100644
--- a/lib/SimpleSAML/Logger/ErrorLogLoggingHandler.php
+++ b/lib/SimpleSAML/Logger/ErrorLogLoggingHandler.php
@@ -58,7 +58,7 @@ class ErrorLogLoggingHandler implements LoggingHandlerInterface
      * @param string $format The format used for logs.
      * @return void
      */
-    public function setLogFormat($format)
+    public function setLogFormat(string $format) : void
     {
         // we don't need the format here
     }
@@ -71,7 +71,7 @@ class ErrorLogLoggingHandler implements LoggingHandlerInterface
      * @param string $string The formatted message to log.
      * @return void
      */
-    public function log($level, $string)
+    public function log(int $level, string $string) : void
     {
         if (array_key_exists($level, self::$levelNames)) {
             $levelName = self::$levelNames[$level];
diff --git a/lib/SimpleSAML/Logger/FileLoggingHandler.php b/lib/SimpleSAML/Logger/FileLoggingHandler.php
index 745a1ed6a02db92cf6acf1b7ea284bd72bc3c93d..659b06b86f163b1b97c25ffcaca999f11091aa0e 100644
--- a/lib/SimpleSAML/Logger/FileLoggingHandler.php
+++ b/lib/SimpleSAML/Logger/FileLoggingHandler.php
@@ -82,7 +82,7 @@ class FileLoggingHandler implements LoggingHandlerInterface
      * @param string $format The format used for logs.
      * @return void
      */
-    public function setLogFormat($format)
+    public function setLogFormat(string $format) : void
     {
         $this->format = $format;
     }
@@ -95,7 +95,7 @@ class FileLoggingHandler implements LoggingHandlerInterface
      * @param string $string The formatted message to log.
      * @return void
      */
-    public function log($level, $string)
+    public function log(int $level, string $string) : void
     {
         if (!is_null($this->logFile)) {
             // set human-readable log level. Copied from SimpleSAML\Logger\ErrorLogLoggingHandler.
diff --git a/lib/SimpleSAML/Logger/LoggingHandlerInterface.php b/lib/SimpleSAML/Logger/LoggingHandlerInterface.php
index 3681c26248fc3e9b07b2b36ec62da9483d1e9bf7..16585d6a699c32481d0b444f1341a08b2bfb04b9 100644
--- a/lib/SimpleSAML/Logger/LoggingHandlerInterface.php
+++ b/lib/SimpleSAML/Logger/LoggingHandlerInterface.php
@@ -30,7 +30,7 @@ interface LoggingHandlerInterface
      * @param string $string The message to log.
      * @return void
      */
-    public function log($level, $string);
+    public function log(int $level, string $string) : void;
 
 
     /**
@@ -39,5 +39,5 @@ interface LoggingHandlerInterface
      * @param string $format The format used for logs.
      * @return void
      */
-    public function setLogFormat($format);
+    public function setLogFormat(string $format) : void;
 }
diff --git a/lib/SimpleSAML/Logger/SyslogLoggingHandler.php b/lib/SimpleSAML/Logger/SyslogLoggingHandler.php
index 49da62d8296d11a9ecbb78b8326a7587113ac20f..57ad7d3403ad566555b68fda8c65d429f23361b2 100644
--- a/lib/SimpleSAML/Logger/SyslogLoggingHandler.php
+++ b/lib/SimpleSAML/Logger/SyslogLoggingHandler.php
@@ -49,7 +49,7 @@ class SyslogLoggingHandler implements LoggingHandlerInterface
      * @param string $format The format used for logs.
      * @return void
      */
-    public function setLogFormat($format)
+    public function setLogFormat(string $format) : void
     {
         $this->format = $format;
     }
@@ -62,7 +62,7 @@ class SyslogLoggingHandler implements LoggingHandlerInterface
      * @param string $string The formatted message to log.
      * @return void
      */
-    public function log($level, $string)
+    public function log(int $level, string $string) : void
     {
         // changing log level to supported levels if OS is Windows
         if ($this->isWindows) {