diff --git a/api/controllers/files/tool_files.py b/api/controllers/files/tool_files.py
index 104b7cd9bb..a298701a2f 100644
--- a/api/controllers/files/tool_files.py
+++ b/api/controllers/files/tool_files.py
@@ -42,10 +42,10 @@ class ToolFilePreviewApi(Resource):
             stream,
             mimetype=tool_file.mimetype,
             direct_passthrough=True,
-            headers={
-                "Content-Length": str(tool_file.size),
-            },
+            headers={},
         )
+        if tool_file.size > 0:
+            response.headers["Content-Length"] = str(tool_file.size)
         if args["as_attachment"]:
             response.headers["Content-Disposition"] = f"attachment; filename={tool_file.name}"
 
diff --git a/api/controllers/web/file.py b/api/controllers/web/file.py
index c029a07707..6eeaa0e3f0 100644
--- a/api/controllers/web/file.py
+++ b/api/controllers/web/file.py
@@ -46,7 +46,7 @@ class RemoteFileInfoApi(WebApiResource):
             response = ssrf_proxy.head(decoded_url)
             return {
                 "file_type": response.headers.get("Content-Type", "application/octet-stream"),
-                "file_length": int(response.headers.get("Content-Length", 0)),
+                "file_length": int(response.headers.get("Content-Length", -1)),
             }
         except Exception as e:
             return {"error": str(e)}, 400