diff --git a/x/babylon/contract/in_message.go b/x/babylon/contract/in_message.go
index 2905d40..d7df60b 100644
--- a/x/babylon/contract/in_message.go
+++ b/x/babylon/contract/in_message.go
@@ -1,11 +1,18 @@
 package contract
 
-// CustomMsg is a message sent from a smart contract to the Babylon module
-// TODO: implement
-type CustomMsg struct {
-	Test *TestMsg `json:"test,omitempty"`
-}
+import (
+	wasmvmtypes "github.com/CosmWasm/wasmvm/v2/types"
+)
 
-type TestMsg struct {
-	Placeholder string `json:"placeholder,omitempty"`
-}
+// CustomMsg is a message sent from a smart contract to the Babylon module
+type (
+	CustomMsg struct {
+		MintRewards *MintRewardsMsg `json:"mint_rewards,omitempty"`
+	}
+	// MintRewardsMsg mints the specified number of block rewards,
+	// and sends them to the specified recipient (typically, the staking contract)
+	MintRewardsMsg struct {
+		Amount    wasmvmtypes.Coin `json:"amount"`
+		Recipient string           `json:"recipient"`
+	}
+)
diff --git a/x/babylon/keeper/handler_plugin.go b/x/babylon/keeper/handler_plugin.go
index a7c655f..5a6534d 100644
--- a/x/babylon/keeper/handler_plugin.go
+++ b/x/babylon/keeper/handler_plugin.go
@@ -55,7 +55,7 @@ func (h CustomMsgHandler) DispatchMsg(ctx sdk.Context, contractAddr sdk.AccAddre
 	if err := json.Unmarshal(msg.Custom, &customMsg); err != nil {
 		return nil, nil, nil, sdkerrors.ErrJSONUnmarshal.Wrap("custom message")
 	}
-	if customMsg.Test == nil {
+	if customMsg.MintRewards == nil {
 		// not our message type
 		return nil, nil, nil, wasmtypes.ErrUnknownMsg
 	}
@@ -64,10 +64,10 @@ func (h CustomMsgHandler) DispatchMsg(ctx sdk.Context, contractAddr sdk.AccAddre
 		return nil, nil, nil, sdkerrors.ErrUnauthorized.Wrapf("contract has no permission for Babylon operations")
 	}
 
-	return h.handleTestMsg(ctx, contractAddr, customMsg.Test)
+	return h.handleMintRewardsMsg(ctx, contractAddr, customMsg.MintRewards)
 }
 
-func (h CustomMsgHandler) handleTestMsg(ctx sdk.Context, actor sdk.AccAddress, testMsg *contract.TestMsg) ([]sdk.Event, [][]byte, [][]*codectypes.Any, error) {
+func (h CustomMsgHandler) handleMintRewardsMsg(ctx sdk.Context, actor sdk.AccAddress, mintRewardsMsg *contract.MintRewardsMsg) ([]sdk.Event, [][]byte, [][]*codectypes.Any, error) {
 	return []sdk.Event{}, nil, nil, nil
 }