diff --git a/cardano-api/gen/Test/Gen/Cardano/Api/Typed.hs b/cardano-api/gen/Test/Gen/Cardano/Api/Typed.hs
index e699e091ed8..91b0cd8d880 100644
--- a/cardano-api/gen/Test/Gen/Cardano/Api/Typed.hs
+++ b/cardano-api/gen/Test/Gen/Cardano/Api/Typed.hs
@@ -608,7 +608,7 @@ genTxBodyContent era = do
   txMetadata <- genTxMetadataInEra era
   txAuxScripts <- genTxAuxScripts era
   let txExtraKeyWits = TxExtraKeyWitnessesNone --TODO: Alonzo era: Generate witness key hashes
-  txProtocolParams <- BuildTxWith <$> Gen.maybe genProtocolParameters
+  txProtocolParams <- BuildTxWith <$> Gen.maybe (genProtocolParameters era)
   txWithdrawals <- genTxWithdrawals era
   txCertificates <- genTxCertificates era
   txUpdateProposal <- genTxUpdateProposal era
@@ -809,8 +809,8 @@ genPraosNonce = makePraosNonce <$> Gen.bytes (Range.linear 0 32)
 genMaybePraosNonce :: Gen (Maybe PraosNonce)
 genMaybePraosNonce = Gen.maybe genPraosNonce
 
-genProtocolParameters :: Gen ProtocolParameters
-genProtocolParameters = do
+genProtocolParameters :: CardanoEra era -> Gen ProtocolParameters
+genProtocolParameters era = do
   protocolParamProtocolVersion <- (,) <$> genNat <*> genNat
   protocolParamDecentralization <- Gen.maybe genRational
   protocolParamExtraPraosEntropy <- genMaybePraosNonce
@@ -838,7 +838,7 @@ genProtocolParameters = do
   protocolParamMaxValueSize <- Gen.maybe genNat
   protocolParamCollateralPercent <- Gen.maybe genNat
   protocolParamMaxCollateralInputs <- Gen.maybe genNat
-  protocolParamUTxOCostPerByte <- Gen.maybe genLovelace
+  protocolParamUTxOCostPerByte <- sequence $ protocolUTxOCostPerByteSupportedInEra era $> genLovelace
 
   pure ProtocolParameters {..}
 
diff --git a/cardano-api/test/Test/Cardano/Api/Typed/JSON.hs b/cardano-api/test/Test/Cardano/Api/Typed/JSON.hs
index 1ab7048d751..e6c6b4c96eb 100644
--- a/cardano-api/test/Test/Cardano/Api/Typed/JSON.hs
+++ b/cardano-api/test/Test/Cardano/Api/Typed/JSON.hs
@@ -8,6 +8,8 @@ module Test.Cardano.Api.Typed.JSON
   ( tests
   ) where
 
+import           Cardano.Api
+
 import           Data.Aeson (eitherDecode, encode)
 
 import           Hedgehog (Property, forAll, tripping)
@@ -28,7 +30,8 @@ prop_roundtrip_praos_nonce_JSON = H.property $ do
 
 prop_roundtrip_protocol_parameters_JSON :: Property
 prop_roundtrip_protocol_parameters_JSON = H.property $ do
-  pp <- forAll genProtocolParameters
+  AnyCardanoEra era <- forAll $ Gen.element [minBound .. maxBound]
+  pp <- forAll (genProtocolParameters era)
   tripping pp encode eitherDecode
 
 -- -----------------------------------------------------------------------------