diff --git a/core.js b/core.js
index 6ff2fbed..b69d1087 100644
--- a/core.js
+++ b/core.js
@@ -477,6 +477,7 @@ class FileTypeParser {
 			const brandMajor = this.buffer.toString('binary', 8, 12).replace('\0', ' ').trim();
 			switch (brandMajor) {
 				case 'avif':
+				case 'avis':
 					return {ext: 'avif', mime: 'image/avif'};
 				case 'mif1':
 					return {ext: 'heic', mime: 'image/heif'};
diff --git a/fixture/fixture-sequence.avif b/fixture/fixture-sequence.avif
new file mode 100644
index 00000000..8a0956df
Binary files /dev/null and b/fixture/fixture-sequence.avif differ
diff --git a/test.js b/test.js
index ddf8d563..b526ad1a 100644
--- a/test.js
+++ b/test.js
@@ -177,6 +177,7 @@ const names = {
 	],
 	avif: [
 		'fixture-yuv420-8bit', // Multiple bit-depths and/or subsamplings
+		'fixture-sequence',
 	],
 	eps: [
 		'fixture',