diff --git a/fastapi/responses.py b/fastapi/responses.py
index 65d0ba394..c915cc7cb 100644
--- a/fastapi/responses.py
+++ b/fastapi/responses.py
@@ -66,6 +66,6 @@ class BSONResponse(Response):
 
     media_type = "application/bson"
 
-    def render(self, content: Any) -> bytes:
+    def render(self, content: Any) -> Any:
         assert bson is not None, "bson must be installed to use BSONResponse"
         return bson.dumps(content)
diff --git a/pyproject.toml b/pyproject.toml
index 1c540e2f6..658a62dba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -92,6 +92,8 @@ all = [
     "ujson >=4.0.1,!=4.0.2,!=4.1.0,!=4.2.0,!=4.3.0,!=5.0.0,!=5.1.0",
     # For ORJSONResponse
     "orjson >=3.2.1",
+    # For BSONResponse
+    "bson >=0.5.10",
     # To validate email fields
     "email-validator >=2.0.0",
     # Uvicorn with uvloop