diff --git a/src/Log/ErrorLogLogger.php b/src/Log/ErrorLogLogger.php
index db05052d028..e251f67fa51 100644
--- a/src/Log/ErrorLogLogger.php
+++ b/src/Log/ErrorLogLogger.php
@@ -62,7 +62,7 @@ private function interpolate(string $message, array $context = array()) : string
      *
      * @throws \Psr\Log\InvalidArgumentException
      */
-    public function log($level, $message, array $context = array())
+    public function log($level, $message, array $context = array()): void
     {
         // LogLevel consts are strings, not integers, so we need to
         // be explicit about which are used instead of doing a < or >