diff --git a/tests/acceptance/features/bootstrap/ArchiverContext.php b/tests/acceptance/features/bootstrap/ArchiverContext.php
index dd93dc834..4ebd96b26 100644
--- a/tests/acceptance/features/bootstrap/ArchiverContext.php
+++ b/tests/acceptance/features/bootstrap/ArchiverContext.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * ownCloud
  *
@@ -207,7 +207,7 @@ class ArchiverContext implements Context {
 	 *
 	 * @throws Exception
 	 */
-	public function theDownloadedArchiveShouldContainTheseFiles(string $type, TableNode $expectedFiles) {
+	public function theDownloadedArchiveShouldContainTheseFiles(string $type, TableNode $expectedFiles):void {
 		$this->featureContext->verifyTableNodeColumns($expectedFiles, ['name', 'content']);
 		$tempFile = \tempnam(\sys_get_temp_dir(), 'OcAcceptanceTests_');
 		\unlink($tempFile); // we only need the name
diff --git a/tests/acceptance/features/bootstrap/RevaContext.php b/tests/acceptance/features/bootstrap/RevaContext.php
index da6aa015e..b74ff023d 100644
--- a/tests/acceptance/features/bootstrap/RevaContext.php
+++ b/tests/acceptance/features/bootstrap/RevaContext.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * ownCloud
  *
diff --git a/tests/acceptance/features/bootstrap/SpacesContext.php b/tests/acceptance/features/bootstrap/SpacesContext.php
index 7868e82c9..d9e639259 100644
--- a/tests/acceptance/features/bootstrap/SpacesContext.php
+++ b/tests/acceptance/features/bootstrap/SpacesContext.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * ownCloud
  *
@@ -163,7 +163,7 @@ class SpacesContext implements Context {
 	 * @throws Exception
 	 */
 	public function getSpaceByNameFromResponse(string $name): array {
-		$response = json_decode($this->featureContext->getResponse()->getBody(), true, 512, JSON_THROW_ON_ERROR);
+		$response = json_decode((string)$this->featureContext->getResponse()->getBody(), true, 512, JSON_THROW_ON_ERROR);
 		$spaceAsArray = $response;
 		if (isset($response['name']) && $response['name'] === $name) {
 			return $response;
diff --git a/tests/acceptance/features/bootstrap/bootstrap.php b/tests/acceptance/features/bootstrap/bootstrap.php
index 7d4158c2b..ec7e80734 100644
--- a/tests/acceptance/features/bootstrap/bootstrap.php
+++ b/tests/acceptance/features/bootstrap/bootstrap.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /**
  * ownCloud
  *