diff --git a/build/params_testground.go b/build/params_testground.go
index 982d71b68..0a4c010e0 100644
--- a/build/params_testground.go
+++ b/build/params_testground.go
@@ -22,6 +22,10 @@ var (
 	BlocksPerEpoch       = uint64(builtin.ExpectedLeadersPerEpoch)
 	BlockMessageLimit    = 512
 	BlockGasLimit        = int64(100_000_000_000)
+	BlockGasTarget = int64(BlockGasLimit / 2)
+	BaseFeeMaxChangeDenom = int64(8) // 12.5%
+	InitialBaseFee = int64(100e6)
+	MinimumBaseFee = int64(100)
 	BlockDelaySecs       = uint64(builtin.EpochDurationSeconds)
 	PropagationDelaySecs = uint64(6)
 
diff --git a/node/impl/full/gas.go b/node/impl/full/gas.go
index b7f443c0a..bd6e8793c 100644
--- a/node/impl/full/gas.go
+++ b/node/impl/full/gas.go
@@ -125,7 +125,7 @@ func (a *GasAPI) GasEstimateGasLimit(ctx context.Context, msgIn *types.Message,
 
 	msg := *msgIn
 	msg.GasLimit = build.BlockGasLimit
-	msg.GasFeeCap = types.NewInt(build.MinimumBaseFee + 1)
+	msg.GasFeeCap = types.NewInt(uint64(build.MinimumBaseFee) + 1)
 	msg.GasPremium = types.NewInt(1)
 
 	currTs := a.Chain.GetHeaviestTipSet()