diff --git a/includes/StreamFile.php b/includes/StreamFile.php
index 97a07ca78be..0d4290718ce 100644
--- a/includes/StreamFile.php
+++ b/includes/StreamFile.php
@@ -122,7 +122,7 @@ class StreamFile {
 		// Use the extension only, rather than magic numbers, to avoid opening
 		// up vulnerabilities due to uploads of files with allowed extensions
 		// but disallowed types.
-		$type = $magic->guessTypesForExtension( $ext );
+		$type = $magic->getMimeTypeFromExtensionOrNull( $ext );
 
 		/**
 		 * Double-check some security settings that were done on upload but might
diff --git a/includes/api/ApiFormatBase.php b/includes/api/ApiFormatBase.php
index 17a9d73ba4e..283df80761e 100644
--- a/includes/api/ApiFormatBase.php
+++ b/includes/api/ApiFormatBase.php
@@ -75,9 +75,9 @@ abstract class ApiFormatBase extends ApiBase {
 		} elseif ( $this->getIsHtml() ) {
 			return 'api-result.html';
 		} else {
-			$exts = MediaWikiServices::getInstance()->getMimeAnalyzer()
-				->getExtensionsForType( $this->getMimeType() );
-			$ext = $exts ? strtok( $exts, ' ' ) : strtolower( $this->mFormat );
+			$mimeAnalyzer = MediaWikiServices::getInstance()->getMimeAnalyzer();
+			$ext = $mimeAnalyzer->getExtensionFromMimeTypeOrNull( $this->getMimeType() )
+				?? strtolower( $this->mFormat );
 			return "api-result.$ext";
 		}
 	}
diff --git a/includes/changes/ChannelFeed.php b/includes/changes/ChannelFeed.php
index 28e87c2dcce..80d2db75bbd 100644
--- a/includes/changes/ChannelFeed.php
+++ b/includes/changes/ChannelFeed.php
@@ -91,9 +91,8 @@ abstract class ChannelFeed extends FeedItem {
 		header( "Content-type: $mimetype; charset=UTF-8" );
 
 		// Set a sane filename
-		$exts = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer()
-			->getExtensionsForType( $mimetype );
-		$ext = $exts ? strtok( $exts, ' ' ) : 'xml';
+		$mimeAnalyzer = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
+		$ext = $mimeAnalyzer->getExtensionFromMimeTypeOrNull( $mimetype ) ?? 'xml';
 		header( "Content-Disposition: inline; filename=\"feed.{$ext}\"" );
 
 		if ( $wgVaryOnXFP ) {
diff --git a/includes/filebackend/FileBackendGroup.php b/includes/filebackend/FileBackendGroup.php
index ab49ea10079..92313b03488 100644
--- a/includes/filebackend/FileBackendGroup.php
+++ b/includes/filebackend/FileBackendGroup.php
@@ -291,7 +291,7 @@ class FileBackendGroup {
 	public function guessMimeInternal( $storagePath, $content, $fsPath ) {
 		// Trust the extension of the storage path (caller must validate)
 		$ext = FileBackend::extensionFromPath( $storagePath );
-		$type = $this->mimeAnalyzer->guessTypesForExtension( $ext );
+		$type = $this->mimeAnalyzer->getMimeTypeFromExtensionOrNull( $ext );
 		// For files without a valid extension (or one at all), inspect the contents
 		if ( !$type && $fsPath ) {
 			$type = $this->mimeAnalyzer->guessMimeType( $fsPath, false );
diff --git a/includes/filerepo/file/ForeignAPIFile.php b/includes/filerepo/file/ForeignAPIFile.php
index 056aeb519f3..c578b4c85ed 100644
--- a/includes/filerepo/file/ForeignAPIFile.php
+++ b/includes/filerepo/file/ForeignAPIFile.php
@@ -292,7 +292,7 @@ class ForeignAPIFile extends File {
 	public function getMimeType() {
 		if ( !isset( $this->mInfo['mime'] ) ) {
 			$magic = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
-			$this->mInfo['mime'] = $magic->guessTypesForExtension( $this->getExtension() );
+			$this->mInfo['mime'] = $magic->getMimeTypeFromExtensionOrNull( $this->getExtension() );
 		}
 
 		return $this->mInfo['mime'];
diff --git a/includes/media/DjVuHandler.php b/includes/media/DjVuHandler.php
index d937505fd22..4a024e23249 100644
--- a/includes/media/DjVuHandler.php
+++ b/includes/media/DjVuHandler.php
@@ -362,7 +362,7 @@ class DjVuHandler extends ImageHandler {
 		static $mime;
 		if ( !isset( $mime ) ) {
 			$magic = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
-			$mime = $magic->guessTypesForExtension( $wgDjvuOutputExtension );
+			$mime = $magic->getMimeTypeFromExtensionOrNull( $wgDjvuOutputExtension );
 		}
 
 		return [ $wgDjvuOutputExtension, $mime ];
diff --git a/includes/media/MediaHandler.php b/includes/media/MediaHandler.php
index 6239bf99d99..0e344724776 100644
--- a/includes/media/MediaHandler.php
+++ b/includes/media/MediaHandler.php
@@ -297,9 +297,9 @@ abstract class MediaHandler {
 		if ( !$ext || $magic->isMatchingExtension( $ext, $mime ) === false ) {
 			// The extension is not valid for this MIME type and we do
 			// recognize the MIME type
-			$extensions = $magic->getExtensionsForType( $mime );
-			if ( $extensions ) {
-				return [ strtok( $extensions, ' ' ), $mime ];
+			$knownExt = $magic->getExtensionFromMimeTypeOrNull( $mime );
+			if ( $knownExt !== null ) {
+				return [ $knownExt, $mime ];
 			}
 		}
 
diff --git a/includes/specials/SpecialMediaStatistics.php b/includes/specials/SpecialMediaStatistics.php
index af8103c68ce..b03a6a7d70a 100644
--- a/includes/specials/SpecialMediaStatistics.php
+++ b/includes/specials/SpecialMediaStatistics.php
@@ -241,17 +241,15 @@ class SpecialMediaStatistics extends QueryPage {
 	 */
 	private function getExtensionList( $mime ) {
 		$exts = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer()
-			->getExtensionsForType( $mime );
-		if ( $exts === null ) {
+			->getExtensionsFromMimeType( $mime );
+		if ( !$exts ) {
 			return '';
 		}
-		$extArray = explode( ' ', $exts );
-		$extArray = array_unique( $extArray );
-		foreach ( $extArray as &$ext ) {
+		foreach ( $exts as &$ext ) {
 			$ext = htmlspecialchars( '.' . $ext );
 		}
 
-		return $this->getLanguage()->commaList( $extArray );
+		return $this->getLanguage()->commaList( $exts );
 	}
 
 	/**
diff --git a/includes/upload/UploadBase.php b/includes/upload/UploadBase.php
index 4cc96b62b20..d39a6310ed1 100644
--- a/includes/upload/UploadBase.php
+++ b/includes/upload/UploadBase.php
@@ -444,7 +444,7 @@ abstract class UploadBase {
 				fclose( $fp );
 
 				$magic = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
-				$extMime = $magic->guessTypesForExtension( $this->mFinalExtension );
+				$extMime = $magic->getMimeTypeFromExtensionOrNull( $this->mFinalExtension );
 				$ieTypes = $magic->getIEMimeTypes( $this->mTempPath, $chunk, $extMime );
 				foreach ( $ieTypes as $ieType ) {
 					if ( $this->checkFileExtension( $ieType, $wgMimeTypeBlacklist ) ) {
@@ -1021,10 +1021,10 @@ abstract class UploadBase {
 			$mime = $magic->guessMimeType( $this->mTempPath );
 			if ( $mime !== 'unknown/unknown' ) {
 				# Get a space separated list of extensions
-				$extList = $magic->getExtensionsForType( $mime );
-				if ( $extList ) {
+				$mimeExt = $magic->getExtensionFromMimeTypeOrNull( $mime );
+				if ( $mimeExt !== null ) {
 					# Set the extension to the canonical extension
-					$this->mFinalExtension = strtok( $extList, ' ' );
+					$this->mFinalExtension = $mimeExt;
 
 					# Fix up the other variables
 					$this->mFilteredName .= ".{$this->mFinalExtension}";
diff --git a/includes/upload/UploadStash.php b/includes/upload/UploadStash.php
index a4d5c721333..833b1ce1bdd 100644
--- a/includes/upload/UploadStash.php
+++ b/includes/upload/UploadStash.php
@@ -485,10 +485,7 @@ class UploadStash {
 			// If not, assume that it should be related to the MIME type of the original file.
 			$magic = MediaWiki\MediaWikiServices::getInstance()->getMimeAnalyzer();
 			$mimeType = $magic->guessMimeType( $path );
-			$extensions = $magic->getExtensionsForType( $mimeType );
-			if ( $extensions !== null ) {
-				$extension = strtok( $extensions, ' ' );
-			}
+			$extension = $magic->getExtensionFromMimeTypeOrNull( $mimeType );
 		}
 
 		if ( $extension === null ) {
diff --git a/tests/phpunit/includes/libs/mime/MimeAnalyzerTest.php b/tests/phpunit/includes/libs/mime/MimeAnalyzerTest.php
index 5fe024b8b2f..74c484045e5 100644
--- a/tests/phpunit/includes/libs/mime/MimeAnalyzerTest.php
+++ b/tests/phpunit/includes/libs/mime/MimeAnalyzerTest.php
@@ -208,7 +208,7 @@ class MimeAnalyzerTest extends PHPUnit\Framework\TestCase {
 	 * The empty string is not a MIME type and should not be mapped to a file extension.
 	 */
 	public function testNoEmptyStringMimeType() {
-		$this->assertNull( $this->mimeAnalyzer->getExtensionsForType( '' ) );
+		$this->assertSame( [], $this->mimeAnalyzer->getExtensionsFromMimeType( '' ) );
 	}
 
 	/**
@@ -227,7 +227,8 @@ class MimeAnalyzerTest extends PHPUnit\Framework\TestCase {
 			},
 		] );
 		$this->assertSame( MEDIATYPE_OFFICE, $mimeAnalyzer->findMediaType( '.fake_extension' ) );
-		$this->assertSame( 'fake/mime', $mimeAnalyzer->getTypesForExtension( 'no_such_extension' ) );
+		$this->assertSame(
+			'fake/mime', $mimeAnalyzer->getMimeTypeFromExtensionOrNull( 'no_such_extension' ) );
 	}
 
 	public function testGetMimeTypesFromExtension() {
diff --git a/tests/phpunit/unit/includes/filebackend/FileBackendGroupTestTrait.php b/tests/phpunit/unit/includes/filebackend/FileBackendGroupTestTrait.php
index 08190e7eeb0..3530acec88e 100644
--- a/tests/phpunit/unit/includes/filebackend/FileBackendGroupTestTrait.php
+++ b/tests/phpunit/unit/includes/filebackend/FileBackendGroupTestTrait.php
@@ -389,7 +389,7 @@ trait FileBackendGroupTestTrait {
 	 * @param string|null $content
 	 * @param string|null $fsPath
 	 * @param string|null $expectedExtensionType Expected return of
-	 *   MimeAnalyzer::guessTypesForExtension
+	 *   MimeAnalyzer::getMimeTypeFromExtensionOrNull
 	 * @param string|null $expectedGuessedMimeType Expected return value of
 	 *   MimeAnalyzer::guessMimeType (null if expected not to be called)
 	 */
@@ -401,7 +401,7 @@ trait FileBackendGroupTestTrait {
 		$expectedGuessedMimeType
 	) {
 		$mimeAnalyzer = $this->createMock( MimeAnalyzer::class );
-		$mimeAnalyzer->expects( $this->once() )->method( 'guessTypesForExtension' )
+		$mimeAnalyzer->expects( $this->once() )->method( 'getMimeTypeFromExtensionOrNull' )
 			->willReturn( $expectedExtensionType );
 		$tmpFileFactory = $this->createMock( TempFSFileFactory::class );
 
@@ -425,7 +425,7 @@ trait FileBackendGroupTestTrait {
 		}
 
 		$mimeAnalyzer->expects( $this->never() )
-			->method( $this->anythingBut( 'guessTypesForExtension', 'guessMimeType' ) );
+			->method( $this->anythingBut( 'getMimeTypeFromExtensionOrNull', 'guessMimeType' ) );
 		$tmpFileFactory->expects( $this->never() )
 			->method( $this->anythingBut( 'newTempFSFile' ) );