diff --git a/mitmproxy2swagger/mitmproxy2swagger.py b/mitmproxy2swagger/mitmproxy2swagger.py
index d5a1449..26b1770 100644
--- a/mitmproxy2swagger/mitmproxy2swagger.py
+++ b/mitmproxy2swagger/mitmproxy2swagger.py
@@ -313,7 +313,7 @@ def main(override_args: Sequence[str] | None = None):
 
                 swagger["paths"][path_template_to_set][method]["responses"]["200"] = {
                     "description": "OK",
-                    "content": {content_type: {}},
+                    "content": ("content-type", ""),
                 }
 
     except FlowReadException as e: