diff --git a/google/generativeai/files.py b/google/generativeai/files.py
index 0e8a8ed27..c0d8e1e0a 100644
--- a/google/generativeai/files.py
+++ b/google/generativeai/files.py
@@ -28,6 +28,8 @@
 
 __all__ = ["upload_file", "get_file", "list_files", "delete_file"]
 
+mimetypes.add_type("image/webp", ".webp")
+
 
 def upload_file(
     path: str | pathlib.Path | os.PathLike,
diff --git a/tests/test_files.py b/tests/test_files.py
index 7d9139450..063f1ce3a 100644
--- a/tests/test_files.py
+++ b/tests/test_files.py
@@ -139,3 +139,10 @@ def test_video_metadata(self):
     def test_to_file_data(self, file_data):
         file_data = file_types.to_file_data(file_data)
         self.assertEqual(protos.FileData(file_uri="https://test_uri"), file_data)
+
+    def test_webp_mimetype(self):
+        self.responses["create_file"].append(protos.File())
+
+        response = genai.upload_file("test.webp")
+
+        self.assertEqual("image/webp", self.observed_requests[0]["mime_type"])