diff --git a/src/dockerflow/fastapi/middleware.py b/src/dockerflow/fastapi/middleware.py
index 9096de9..02a844e 100644
--- a/src/dockerflow/fastapi/middleware.py
+++ b/src/dockerflow/fastapi/middleware.py
@@ -59,7 +59,7 @@ def __init__(
             logger.setLevel(logging.INFO)
             handler = logging.StreamHandler(sys.stdout)
             handler.setLevel(logging.INFO)
-            handler.setFormatter(JsonLogFormatter)
+            handler.setFormatter(JsonLogFormatter())
             logger.addHandler(handler)
         self.logger = logger
 
diff --git a/tests/fastapi/test_fastapi.py b/tests/fastapi/test_fastapi.py
index 3a496e1..4ec97de 100644
--- a/tests/fastapi/test_fastapi.py
+++ b/tests/fastapi/test_fastapi.py
@@ -47,7 +47,21 @@ def test_lbheartbeat_head(client):
     assert response.content == b""
 
 
-def test_mozlog(app, client, caplog):
+def test_mozlog_record_formatted_as_json(app, client, capsys):
+    app.state.DOCKERFLOW_SUMMARY_LOG_QUERYSTRING = True
+
+    client.get(
+        "/__lbheartbeat__?x=شكر",
+        headers={
+            "User-Agent": "dockerflow/tests",
+            "Accept-Language": "en-US",
+        },
+    )
+    stdout = capsys.readouterr().out
+    assert json.loads(stdout)
+
+
+def test_mozlog_record_attrs(app, client, caplog):
     app.state.DOCKERFLOW_SUMMARY_LOG_QUERYSTRING = True
 
     client.get(