diff --git a/pkgs/mime/lib/src/default_extension_map.dart b/pkgs/mime/lib/src/default_extension_map.dart
index 287c957dc..5d17732eb 100644
--- a/pkgs/mime/lib/src/default_extension_map.dart
+++ b/pkgs/mime/lib/src/default_extension_map.dart
@@ -297,6 +297,7 @@ const Map<String, String> defaultExtensionMap = <String, String>{
   'grv': 'application/vnd.groove-injector',
   'grxml': 'application/srgs+xml',
   'gsf': 'application/x-font-ghostscript',
+  'gsheet': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
   'gtar': 'application/x-gtar',
   'gtm': 'application/vnd.groove-tool-message',
   'gtw': 'model/vnd.gtw',
diff --git a/pkgs/mime/test/mime_type_test.dart b/pkgs/mime/test/mime_type_test.dart
index 23cb34af3..312d4c9fa 100644
--- a/pkgs/mime/test/mime_type_test.dart
+++ b/pkgs/mime/test/mime_type_test.dart
@@ -54,6 +54,10 @@ void main() {
       _expectMimeType('file.markdown', 'text/markdown');
       _expectMimeType('file.heif', 'image/heif');
       _expectMimeType('file.heic', 'image/heic');
+      _expectMimeType(
+        'file.gsheet',
+        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+      );
     });
 
     test('unknown-mime-type', () {