diff --git a/autoload.php b/autoload.php
index 11f282b43f4..1dc4fec781f 100644
--- a/autoload.php
+++ b/autoload.php
@@ -279,9 +279,6 @@ $wgAutoloadLocalClasses = [
 	'CompareLanguageConverterOutput' => __DIR__ . '/maintenance/compareLanguageConverterOutput.php',
 	'CompareParserCache' => __DIR__ . '/maintenance/compareParserCache.php',
 	'CompareParsers' => __DIR__ . '/maintenance/compareParsers.php',
-	'ComposerInstalled' => __DIR__ . '/includes/libs/composer/ComposerInstalled.php',
-	'ComposerJson' => __DIR__ . '/includes/libs/composer/ComposerJson.php',
-	'ComposerLock' => __DIR__ . '/includes/libs/composer/ComposerLock.php',
 	'CompressOld' => __DIR__ . '/maintenance/storage/compressOld.php',
 	'ConcatenatedGzipHistoryBlob' => __DIR__ . '/includes/historyblob/ConcatenatedGzipHistoryBlob.php',
 	'Config' => __DIR__ . '/includes/config/Config.php',
@@ -3059,6 +3056,9 @@ $wgAutoloadLocalClasses = [
 	'WikiRevision' => __DIR__ . '/includes/import/WikiRevision.php',
 	'WikiStatsOutput' => __DIR__ . '/maintenance/language/StatOutputs.php',
 	'WikiTextStructure' => __DIR__ . '/includes/content/WikiTextStructure.php',
+	'Wikimedia\\Composer\\ComposerInstalled' => __DIR__ . '/includes/libs/composer/ComposerInstalled.php',
+	'Wikimedia\\Composer\\ComposerJson' => __DIR__ . '/includes/libs/composer/ComposerJson.php',
+	'Wikimedia\\Composer\\ComposerLock' => __DIR__ . '/includes/libs/composer/ComposerLock.php',
 	'Wikimedia\\DebugInfo\\AnnotationReader' => __DIR__ . '/includes/libs/DebugInfo/AnnotationReader.php',
 	'Wikimedia\\DebugInfo\\DebugInfoTrait' => __DIR__ . '/includes/libs/DebugInfo/DebugInfoTrait.php',
 	'Wikimedia\\DebugInfo\\DumpUtils' => __DIR__ . '/includes/libs/DebugInfo/DumpUtils.php',
diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index c997af72b15..d061cadc3dd 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -83,6 +83,7 @@ class AutoLoader {
 		'MediaWiki\\Utils\\' => __DIR__ . '/utils/',
 		'MediaWiki\\Widget\\' => __DIR__ . '/widget/',
 		'Wikimedia\\' => __DIR__ . '/libs/',
+		'Wikimedia\\Composer\\' => __DIR__ . '/libs/composer/',
 		'Wikimedia\\Http\\' => __DIR__ . '/libs/http/',
 		'Wikimedia\\Rdbms\\Platform\\' => __DIR__ . '/libs/rdbms/platform/',
 		'Wikimedia\\UUID\\' => __DIR__ . '/libs/uuid/',
diff --git a/includes/api/ApiQuerySiteinfo.php b/includes/api/ApiQuerySiteinfo.php
index f0d9404e221..36889d82522 100644
--- a/includes/api/ApiQuerySiteinfo.php
+++ b/includes/api/ApiQuerySiteinfo.php
@@ -40,6 +40,7 @@ use MediaWiki\Utils\ExtensionInfo;
 use MediaWiki\Utils\GitInfo;
 use MediaWiki\Utils\UrlUtils;
 use MediaWiki\WikiMap\WikiMap;
+use Wikimedia\Composer\ComposerInstalled;
 use Wikimedia\ParamValidator\ParamValidator;
 use Wikimedia\Rdbms\ILoadBalancer;
 use Wikimedia\Rdbms\ReadOnlyMode;
diff --git a/includes/composer/LockFileChecker.php b/includes/composer/LockFileChecker.php
index ce3dce005ab..6283d49a24e 100644
--- a/includes/composer/LockFileChecker.php
+++ b/includes/composer/LockFileChecker.php
@@ -21,9 +21,9 @@
 namespace MediaWiki\Composer;
 
 use Composer\Semver\Semver;
-use ComposerJson;
-use ComposerLock;
 use Status;
+use Wikimedia\Composer\ComposerJson;
+use Wikimedia\Composer\ComposerLock;
 
 /**
  * Used to check whether composer-installed dependencies (no-dev) are up-to-date
diff --git a/includes/libs/composer/ComposerInstalled.php b/includes/libs/composer/ComposerInstalled.php
index a708429065d..9c4c2fbc41d 100644
--- a/includes/libs/composer/ComposerInstalled.php
+++ b/includes/libs/composer/ComposerInstalled.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace Wikimedia\Composer;
+
 /**
  * Reads an installed.json file and provides accessors to get what is
  * installed
diff --git a/includes/libs/composer/ComposerJson.php b/includes/libs/composer/ComposerJson.php
index 8772a0c53b8..c380c2ee80c 100644
--- a/includes/libs/composer/ComposerJson.php
+++ b/includes/libs/composer/ComposerJson.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace Wikimedia\Composer;
+
 /**
  * Reads a composer.json file and provides accessors to get
  * its hash and the required dependencies
diff --git a/includes/libs/composer/ComposerLock.php b/includes/libs/composer/ComposerLock.php
index b26fe538f52..4ab3f97f28a 100644
--- a/includes/libs/composer/ComposerLock.php
+++ b/includes/libs/composer/ComposerLock.php
@@ -1,5 +1,7 @@
 <?php
 
+namespace Wikimedia\Composer;
+
 /**
  * Reads a composer.lock file and provides accessors to get
  * its hash and what is installed
diff --git a/includes/specials/SpecialVersion.php b/includes/specials/SpecialVersion.php
index aaa90536aa7..66cb57611b6 100644
--- a/includes/specials/SpecialVersion.php
+++ b/includes/specials/SpecialVersion.php
@@ -23,7 +23,6 @@
 namespace MediaWiki\Specials;
 
 use Closure;
-use ComposerInstalled;
 use ExtensionRegistry;
 use HtmlArmor;
 use Language;
@@ -47,6 +46,7 @@ use ObjectCache;
 use Parser;
 use ParserFactory;
 use Symfony\Component\Yaml\Yaml;
+use Wikimedia\Composer\ComposerInstalled;
 use Wikimedia\Parsoid\Core\SectionMetadata;
 use Wikimedia\Parsoid\Core\TOCData;
 use Wikimedia\Rdbms\IConnectionProvider;
diff --git a/maintenance/checkComposerLockUpToDate.php b/maintenance/checkComposerLockUpToDate.php
index 95a8cbee6b3..33d34bcfb85 100644
--- a/maintenance/checkComposerLockUpToDate.php
+++ b/maintenance/checkComposerLockUpToDate.php
@@ -3,6 +3,8 @@
 require_once __DIR__ . '/Maintenance.php';
 
 use MediaWiki\Composer\LockFileChecker;
+use Wikimedia\Composer\ComposerJson;
+use Wikimedia\Composer\ComposerLock;
 
 /**
  * Checks whether your composer-installed dependencies are up to date
diff --git a/maintenance/convertExtensionToRegistration.php b/maintenance/convertExtensionToRegistration.php
index 4e948f7bc77..7583c579515 100644
--- a/maintenance/convertExtensionToRegistration.php
+++ b/maintenance/convertExtensionToRegistration.php
@@ -1,5 +1,7 @@
 <?php
 
+use Wikimedia\Composer\ComposerJson;
+
 require_once __DIR__ . '/Maintenance.php';
 
 class ConvertExtensionToRegistration extends Maintenance {
@@ -340,9 +342,9 @@ class ConvertExtensionToRegistration extends Maintenance {
 	protected function needsComposerAutoloader( $path ) {
 		$path .= '/composer.json';
 		if ( file_exists( $path ) ) {
-			// assume, that the composer.json file is in the root of the extension path
+			// assume that the composer.json file is in the root of the extension path
 			$composerJson = new ComposerJson( $path );
-			// check, if there are some dependencies in the require section
+			// check if there are some dependencies in the require section
 			if ( $composerJson->getRequiredDependencies() ) {
 				return true;
 			}
diff --git a/tests/phpunit/includes/api/query/ApiQuerySiteinfoTest.php b/tests/phpunit/includes/api/query/ApiQuerySiteinfoTest.php
index 96d24bcccaa..294939a2d9b 100644
--- a/tests/phpunit/includes/api/query/ApiQuerySiteinfoTest.php
+++ b/tests/phpunit/includes/api/query/ApiQuerySiteinfoTest.php
@@ -4,6 +4,7 @@ use MediaWiki\MainConfigNames;
 use MediaWiki\MainConfigSchema;
 use MediaWiki\SiteStats\SiteStats;
 use MediaWiki\Title\Title;
+use Wikimedia\Composer\ComposerInstalled;
 use Wikimedia\Rdbms\LoadBalancer;
 use Wikimedia\TestingAccessWrapper;
 
diff --git a/tests/phpunit/integration/includes/composer/LockFileCheckerTest.php b/tests/phpunit/integration/includes/composer/LockFileCheckerTest.php
index 984142182a0..6a241e016d4 100644
--- a/tests/phpunit/integration/includes/composer/LockFileCheckerTest.php
+++ b/tests/phpunit/integration/includes/composer/LockFileCheckerTest.php
@@ -19,6 +19,8 @@
  */
 
 use MediaWiki\Composer\LockFileChecker;
+use Wikimedia\Composer\ComposerJson;
+use Wikimedia\Composer\ComposerLock;
 
 /**
  * @covers \MediaWiki\Composer\LockFileChecker
diff --git a/tests/phpunit/unit/includes/libs/composer/ComposerInstalledTest.php b/tests/phpunit/unit/includes/libs/composer/ComposerInstalledTest.php
index 50a38009b27..c8786eb03d4 100644
--- a/tests/phpunit/unit/includes/libs/composer/ComposerInstalledTest.php
+++ b/tests/phpunit/unit/includes/libs/composer/ComposerInstalledTest.php
@@ -1,9 +1,11 @@
 <?php
 
+use Wikimedia\Composer\ComposerInstalled;
+
 class ComposerInstalledTest extends PHPUnit\Framework\TestCase {
 	/**
-	 * @covers ComposerInstalled::__construct
-	 * @covers ComposerInstalled::getInstalledDependencies
+	 * @covers Wikimedia\Composer\ComposerInstalled::__construct
+	 * @covers Wikimedia\Composer\ComposerInstalled::getInstalledDependencies
 	 *
 	 * @dataProvider provideInstalled
 	 */
diff --git a/tests/phpunit/unit/includes/libs/composer/ComposerJsonTest.php b/tests/phpunit/unit/includes/libs/composer/ComposerJsonTest.php
index 37bc92ef974..ed0ffb8a17d 100644
--- a/tests/phpunit/unit/includes/libs/composer/ComposerJsonTest.php
+++ b/tests/phpunit/unit/includes/libs/composer/ComposerJsonTest.php
@@ -1,5 +1,7 @@
 <?php
 
+use Wikimedia\Composer\ComposerJson;
+
 class ComposerJsonTest extends PHPUnit\Framework\TestCase {
 
 	private $json;
@@ -10,8 +12,8 @@ class ComposerJsonTest extends PHPUnit\Framework\TestCase {
 	}
 
 	/**
-	 * @covers ComposerJson::__construct
-	 * @covers ComposerJson::getRequiredDependencies
+	 * @covers Wikimedia\Composer\ComposerJson::__construct
+	 * @covers Wikimedia\Composer\ComposerJson::getRequiredDependencies
 	 */
 	public function testGetRequiredDependencies() {
 		$json = new ComposerJson( $this->json );
@@ -32,7 +34,7 @@ class ComposerJsonTest extends PHPUnit\Framework\TestCase {
 
 	/**
 	 * @dataProvider provideNormalizeVersion
-	 * @covers ComposerJson::normalizeVersion
+	 * @covers Wikimedia\Composer\ComposerJson::normalizeVersion
 	 */
 	public function testNormalizeVersion( $input, $expected ) {
 		$this->assertEquals( $expected, ComposerJson::normalizeVersion( $input ) );
diff --git a/tests/phpunit/unit/includes/libs/composer/ComposerLockTest.php b/tests/phpunit/unit/includes/libs/composer/ComposerLockTest.php
index fc7501e41eb..29a585c5aad 100644
--- a/tests/phpunit/unit/includes/libs/composer/ComposerLockTest.php
+++ b/tests/phpunit/unit/includes/libs/composer/ComposerLockTest.php
@@ -1,5 +1,7 @@
 <?php
 
+use Wikimedia\Composer\ComposerLock;
+
 class ComposerLockTest extends PHPUnit\Framework\TestCase {
 
 	private $lock;
@@ -10,8 +12,8 @@ class ComposerLockTest extends PHPUnit\Framework\TestCase {
 	}
 
 	/**
-	 * @covers ComposerLock::__construct
-	 * @covers ComposerLock::getInstalledDependencies
+	 * @covers Wikimedia\Composer\ComposerLock::__construct
+	 * @covers Wikimedia\Composer\ComposerLock::getInstalledDependencies
 	 */
 	public function testGetInstalledDependencies() {
 		$lock = new ComposerLock( $this->lock );