diff --git a/staging_service/app.py b/staging_service/app.py
index 598179e8..167e83cd 100644
--- a/staging_service/app.py
+++ b/staging_service/app.py
@@ -53,6 +53,7 @@
     EXCEL: write_excel,
 }
 
+# The constant in autodetect.Mappings isn't guaranteed to be the string we want.
 JSON_EXTENSION = "json"
 NO_EXTENSION = "missing extension"