diff --git a/.gitattributes b/.gitattributes
index 171d8a5..0a94073 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -41,3 +41,4 @@
 *.caf binary
 *.aac binary
 *.wma binary
+*.au binary
diff --git a/src/AudioFormat.php b/src/AudioFormat.php
index f89c261..a20e8f9 100644
--- a/src/AudioFormat.php
+++ b/src/AudioFormat.php
@@ -19,4 +19,5 @@ final class AudioFormat
     public const CAF = 'caf';
     public const AAC = 'aac';
     public const WMA = 'wma';
+    public const AU = 'au';
 }
diff --git a/src/AudioMimeType.php b/src/AudioMimeType.php
index 73cf690..45c5d07 100644
--- a/src/AudioMimeType.php
+++ b/src/AudioMimeType.php
@@ -19,4 +19,5 @@ final class AudioMimeType
     public const AUDIO_CAF = 'audio/x-caf';
     public const AUDIO_AAC = 'audio/aac';
     public const AUDIO_WMA = 'audio/x-ms-wma';
+    public const AUDIO_AU = 'audio/basic';
 }
diff --git a/src/Detector/AuDetector.php b/src/Detector/AuDetector.php
new file mode 100644
index 0000000..9088194
--- /dev/null
+++ b/src/Detector/AuDetector.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Selective\AudioType\Detector;
+
+use Selective\AudioType\AudioFormat;
+use Selective\AudioType\AudioType;
+use Selective\AudioType\AudioMimeType;
+use SplFileObject;
+
+/**
+ * Detector.
+ */
+final class AuDetector implements AudioDetectorInterface
+{
+    /**
+     * Detect AU audio file
+     *
+     * @param SplFileObject $file The audio file
+     *
+     * @return AudioType|null The audio type
+     */
+    public function detect(SplFileObject $file): ?AudioType
+    {
+        $bytes = (string)$file->fread(4);
+
+        return $bytes === '.snd' ? new AudioType(
+            AudioFormat::AU,
+            AudioMimeType::AUDIO_AU
+        ) : null;
+    }
+}
diff --git a/src/Provider/DefaultAudioProvider.php b/src/Provider/DefaultAudioProvider.php
index 820f497..841de81 100644
--- a/src/Provider/DefaultAudioProvider.php
+++ b/src/Provider/DefaultAudioProvider.php
@@ -14,6 +14,7 @@
 use Selective\AudioType\Detector\CafDetector;
 use Selective\AudioType\Detector\AacDetector;
 use Selective\AudioType\Detector\WmaDetector;
+use Selective\AudioType\Detector\AuDetector;
 
 /**
  * All supported audio formats.
@@ -38,6 +39,7 @@ public function getDetectors(): array
             new CafDetector(),
             new AacDetector(),
             new WmaDetector(),
+            new AuDetector(),
         ];
     }
 }
diff --git a/tests/AudioTypeDetectorTest.php b/tests/AudioTypeDetectorTest.php
index c07cdfb..3f8aacf 100644
--- a/tests/AudioTypeDetectorTest.php
+++ b/tests/AudioTypeDetectorTest.php
@@ -75,6 +75,7 @@ public function providerGetAudioTypeFromFile(): array
             'CAF' => [__DIR__ . '/files/test.caf', AudioFormat::CAF, AudioMimeType::AUDIO_CAF],
             'AAC' => [__DIR__ . '/files/test.aac', AudioFormat::AAC, AudioMimeType::AUDIO_AAC],
             'WMA' => [__DIR__ . '/files/test.wma', AudioFormat::WMA, AudioMimeType::AUDIO_WMA],
+            'AU' => [__DIR__ . '/files/test.au', AudioFormat::AU, AudioMimeType::AUDIO_AU],
         ];
     }
 
diff --git a/tests/files/test.au b/tests/files/test.au
new file mode 100644
index 0000000..cbcfaab
Binary files /dev/null and b/tests/files/test.au differ