diff --git a/x/feemarket/types/codec.go b/x/feemarket/types/codec.go
index 2269b95..a5ec84c 100644
--- a/x/feemarket/types/codec.go
+++ b/x/feemarket/types/codec.go
@@ -6,12 +6,18 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/msgservice"
+
+	"github.com/skip-mev/feemarket/x/feemarket/interfaces"
+	"github.com/skip-mev/feemarket/x/feemarket/plugins/defaultmarket"
 )
 
 // RegisterLegacyAminoCodec registers the necessary x/feemarket interfaces (messages) on the
 // provided LegacyAmino codec.
 func RegisterLegacyAminoCodec(cdc *codec.LegacyAmino) {
 	legacy.RegisterAminoMsg(cdc, &MsgParams{}, "feemarket/MsgParams")
+
+	cdc.RegisterInterface((*interfaces.FeeMarketImplementation)(nil), nil)
+	cdc.RegisterConcrete(&defaultmarket.DefaultMarket{}, "feemarket/DefaultMarket", nil)
 }
 
 // RegisterInterfaces registers the x/feemarket interfaces (messages + msg server) on the
@@ -21,5 +27,11 @@ func RegisterInterfaces(registry types.InterfaceRegistry) {
 		&MsgParams{},
 	)
 
+	registry.RegisterInterface(
+		"feemarket.feemarket.v1.FeeMarketImplementation",
+		(*interfaces.FeeMarketImplementation)(nil),
+		&defaultmarket.DefaultMarket{},
+	)
+
 	msgservice.RegisterMsgServiceDesc(registry, &_Msg_serviceDesc)
 }