diff --git a/eras/conway/impl/src/Cardano/Ledger/Conway/PParams.hs b/eras/conway/impl/src/Cardano/Ledger/Conway/PParams.hs
index b6a9e84adda..82e48cffbfe 100644
--- a/eras/conway/impl/src/Cardano/Ledger/Conway/PParams.hs
+++ b/eras/conway/impl/src/Cardano/Ledger/Conway/PParams.hs
@@ -108,7 +108,7 @@ import Cardano.Ledger.BaseTypes (
   NonNegativeInterval,
   NonZero,
   PositiveInterval,
-  ProtVer (ProtVer),
+  ProtVer (..),
   ToKeyValuePairs (..),
   UnitInterval,
   integralToBounded,
@@ -119,6 +119,7 @@ import Cardano.Ledger.Binary (
   DecCBOR (..),
   EncCBOR (..),
   encodeListLen,
+  natVersion,
  )
 import Cardano.Ledger.Binary.Coders
 import Cardano.Ledger.Coin (Coin (Coin), CompactForm (..), compactCoinOrError, partialCompactCoinL)
@@ -932,6 +933,8 @@ instance ConwayEraPParams ConwayEra where
       , hardforkConwayBootstrapPhase pv
           || isValid ((/= zero) . unCoinPerByte) ppuCoinsPerUTxOByteL
       , ppu /= emptyPParamsUpdate
+      , pvMajor pv < natVersion @11
+          || isValid (/= 0) ppuNOptL
       ]
     where
       isValid ::
diff --git a/eras/dijkstra/impl/src/Cardano/Ledger/Dijkstra/PParams.hs b/eras/dijkstra/impl/src/Cardano/Ledger/Dijkstra/PParams.hs
index 3187e4491d4..24822d5d194 100644
--- a/eras/dijkstra/impl/src/Cardano/Ledger/Dijkstra/PParams.hs
+++ b/eras/dijkstra/impl/src/Cardano/Ledger/Dijkstra/PParams.hs
@@ -541,6 +541,7 @@ instance ConwayEraPParams DijkstraEra where
       , isValid (/= zero) ppuDRepDepositL
       , isValid ((/= zero) . unCoinPerByte) ppuCoinsPerUTxOByteL
       , ppu /= emptyPParamsUpdate
+      , isValid (/= 0) ppuNOptL
       ]
     where
       isValid ::