diff --git a/data-wrapper/v1/csv.ini b/data-wrapper/v1/csv.ini
index 1516841..372ed18 100644
--- a/data-wrapper/v1/csv.ini
+++ b/data-wrapper/v1/csv.ini
@@ -52,6 +52,12 @@
 [exchange]
 value = self().thru(x => _.env(null, 'slim') ? _.pick(x, ['id', 'value']) : x)
 
+# in the hope that all the lines look the same
+[singleton]
+[singleton/validate]
+path = value
+rule = required
+
 [TARDump]
 compress = true
 manifest = fix({version: '1'})