diff --git a/src/agents/models/chatcmpl_converter.py b/src/agents/models/chatcmpl_converter.py
index 77cfc4e1a..61bbbb30b 100644
--- a/src/agents/models/chatcmpl_converter.py
+++ b/src/agents/models/chatcmpl_converter.py
@@ -271,11 +271,16 @@ def extract_all_content(
                     raise UserError(
                         f"Only file_data is supported for input_file {casted_file_param}"
                     )
+                if "filename" not in casted_file_param or not casted_file_param["filename"]:
+                    raise UserError(
+                        f"filename must be provided for input_file {casted_file_param}"
+                    )
                 out.append(
                     File(
                         type="file",
                         file=FileFile(
                             file_data=casted_file_param["file_data"],
+                            filename=casted_file_param["filename"],
                         ),
                     )
                 )