diff --git a/nonebot_plugin_prometheus/api.py b/nonebot_plugin_prometheus/api.py
index dc17f36..7b7073a 100644
--- a/nonebot_plugin_prometheus/api.py
+++ b/nonebot_plugin_prometheus/api.py
@@ -9,7 +9,9 @@
 
 async def metrics(request: Request) -> Response:
     counter.inc()
-    return Response(200, content=generate_latest())
+    return Response(
+        200, headers={"Content-Type": "text/plain"}, content=generate_latest()
+    )
 
 
 def enable_prometheus():
diff --git a/pyproject.toml b/pyproject.toml
index 1bfc6b1..8fad548 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "nonebot-plugin-prometheus"
-version = "0.3.3"
+version = "0.3.4"
 description = "为 NoneBot 和其他插件提供 Prometheus 监控支持"
 readme = "README.md"
 requires-python = ">=3.9, <4.0"