diff --git a/lib/src/utils/mime_type_utils.dart b/lib/src/utils/mime_type_utils.dart
index 2f06052..bda321d 100644
--- a/lib/src/utils/mime_type_utils.dart
+++ b/lib/src/utils/mime_type_utils.dart
@@ -17,9 +17,11 @@ String? lookupMimeType(String path, {List<int>? headerBytes}) {
   return mime.lookupMimeType(path, headerBytes: headerBytes);
 }
 
-String lookupMimeTypeWithDefaultType(String path, {List<int>? headerBytes}) =>
-    lookupMimeType(path, headerBytes: headerBytes) ??
-    'application/octet-stream';
+String lookupMimeTypeWithDefaultType(String path, {List<int>? headerBytes}) {
+  path = path.toLowerCase();
+
+  return lookupMimeType(path, headerBytes: headerBytes) ?? octetStream;
+}
 
 /// This implementation is specific for `file_saver` package.
 MimeType getMimeTypeFromString(String mimeType) {
@@ -76,3 +78,5 @@ MimeType getMimeTypeFromString(String mimeType) {
       return MimeType.OTHER;
   }
 }
+
+const String octetStream = 'application/octet-stream';
diff --git a/pubspec.yaml b/pubspec.yaml
index 2f09c47..81b5c2a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: ardrive_io
 description: A new Flutter package project.
-version: 1.4.4
+version: 1.4.5
 homepage:
 publish_to: none
 
diff --git a/test/src/utils/mime_type_utils_test.dart b/test/src/utils/mime_type_utils_test.dart
index 01a7e0c..c7e3d45 100644
--- a/test/src/utils/mime_type_utils_test.dart
+++ b/test/src/utils/mime_type_utils_test.dart
@@ -35,8 +35,21 @@ void main() {
       'path/to/my/non tar/file.iso': 'application/x-iso9660-image',
       'ardrive.png': 'image/png',
       '.tar.gz': 'application/gzip',
-      'my.non.tar.gz.file': 'application/octet-stream',
-      'where\'s waldo.tar.gz.': 'application/octet-stream',
+      'my.non.tar.gz.file': octetStream,
+      'where\'s waldo.tar.gz.': octetStream,
+    };
+
+    const pathToMimeMappingUpperCase = <String, String?>{
+      '.my.file.TAR.GZ': 'application/gzip',
+      'abcdefghijklmnñopqrstuvwxyz.tar.GZ': 'application/gzip',
+      'path/to/my/file.TAR.GZ': 'application/gzip',
+      'path/to/my/file.GZ': 'application/gzip',
+      'path/to/my/file.tGZ': 'application/gzip',
+      'path/to/my/non tar/file.ISO': 'application/x-iso9660-image',
+      'ardrive.PNG': 'image/png',
+      '.tar.GZ': 'application/gzip',
+      'my.non.tar.GZ.file': octetStream,
+      'where\'s waldo.TAR.gz.': octetStream,
     };
 
     test('returns the expected mime type', () {
@@ -47,12 +60,20 @@ void main() {
       }
     });
 
+    test('returns the expected mime type when written in uppercase', () {
+      for (final path in pathToMimeMappingUpperCase.keys) {
+        final expectedMime = pathToMimeMappingUpperCase[path];
+        final mime = lookupMimeTypeWithDefaultType(path);
+        expect(mime, expectedMime);
+      }
+    });
+
     test(
         'returns the application/octet-stream type when not provided a mime type',
         () {
       final mime =
           lookupMimeTypeWithDefaultType('path/some_file_without_extension');
-      expect(mime, 'application/octet-stream');
+      expect(mime, octetStream);
     });
   });
 }
diff --git a/test/src/utils/path_utils_test.dart b/test/src/utils/path_utils_test.dart
index 06613f1..78d97b7 100644
--- a/test/src/utils/path_utils_test.dart
+++ b/test/src/utils/path_utils_test.dart
@@ -1,5 +1,4 @@
-import 'package:ardrive_io/src/io_exception.dart';
-import 'package:ardrive_io/src/utils/path_utils.dart';
+import 'package:ardrive_io/ardrive_io.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -76,7 +75,7 @@ void main() {
     test('should return the extension from mimetype name without .', () {
       final ext = getFileExtension(
         name: 'file',
-        contentType: 'application/octet-stream',
+        contentType: octetStream,
         withExtensionDot: false,
       );