diff --git a/plugins/Live/tests/Fixtures/ManyVisitsOfSameVisitor.php b/plugins/Live/tests/Fixtures/ManyVisitsOfSameVisitor.php
index d0dfef0d172d..73b68a21d61e 100644
--- a/plugins/Live/tests/Fixtures/ManyVisitsOfSameVisitor.php
+++ b/plugins/Live/tests/Fixtures/ManyVisitsOfSameVisitor.php
@@ -44,7 +44,7 @@ private function trackVisits()
         $t = self::getTracker($this->idSite2, $this->dateTime, $defaultInit = true);
         $t->setTokenAuth(self::getTokenAuth());
         $t->setForceNewVisit();
-        $t->setUserId(101);
+        $t->setUserId('101');
         $t->setUrl('http://example.org/foo/dir/page');
 
         $visitDateTime = Date::factory($this->dateTime)->getDatetime();
diff --git a/tests/LocalTracker.php b/tests/LocalTracker.php
index f4a4bf5da29d..c682985fa9e7 100644
--- a/tests/LocalTracker.php
+++ b/tests/LocalTracker.php
@@ -18,7 +18,7 @@
  */
 class Matomo_LocalTracker extends MatomoTracker
 {
-    protected function sendRequest($url, $method = 'GET', $data = null, $force = false)
+    protected function sendRequest(string $url, string $method = 'GET', $data = null, bool $force = false)
     {
         self::$DEBUG_LAST_REQUESTED_URL = $url;
 
diff --git a/tests/PHPUnit/Fixtures/FewVisitsWithSetVisitorId.php b/tests/PHPUnit/Fixtures/FewVisitsWithSetVisitorId.php
index c283d51d83ea..0b953f230153 100644
--- a/tests/PHPUnit/Fixtures/FewVisitsWithSetVisitorId.php
+++ b/tests/PHPUnit/Fixtures/FewVisitsWithSetVisitorId.php
@@ -146,7 +146,7 @@ private function trackVisitsSetUserId()
         self::checkResponse($t->doTrackPageView('second pageview - by this user id'));
 
         // Request from a different computer not yet logged in, this should not be added to our User ID session
-        $t->setUserId(false);
+        $t->setUserId(null);
         // make sure the Id is not so random as to not fail the test
         $t->setVisitorId('5e15b4d842cc294d');
 
diff --git a/tests/PHPUnit/Framework/Fixture.php b/tests/PHPUnit/Framework/Fixture.php
index 0fef8b643de6..179e008d8c0e 100644
--- a/tests/PHPUnit/Framework/Fixture.php
+++ b/tests/PHPUnit/Framework/Fixture.php
@@ -758,6 +758,8 @@ public static function getTokenAuth()
         if (!empty($user)) {
             return self::ADMIN_USER_TOKEN;
         }
+
+        return null;
     }
 
     public static function createSuperUser($removeExisting = true)