diff --git a/src/runloop_api_client/_base_client.py b/src/runloop_api_client/_base_client.py
index 22e3bc63..6ed767c0 100644
--- a/src/runloop_api_client/_base_client.py
+++ b/src/runloop_api_client/_base_client.py
@@ -518,7 +518,7 @@ def _build_request(
             # so that passing a `TypedDict` doesn't cause an error.
             # https://github.com/microsoft/pyright/issues/3526#event-6715453066
             params=self.qs.stringify(cast(Mapping[str, Any], params)) if params else None,
-            json=json_data,
+            json=json_data if is_given(json_data) else None,
             files=files,
             **kwargs,
         )