diff --git a/app/app.go b/app/app.go
index c0ac68fa..0976b785 100644
--- a/app/app.go
+++ b/app/app.go
@@ -59,7 +59,7 @@ import (
 	atomoneante "github.com/atomone-hub/atomone/ante"
 	"github.com/atomone-hub/atomone/app/keepers"
 	"github.com/atomone-hub/atomone/app/upgrades"
-	v4 "github.com/atomone-hub/atomone/app/upgrades/v4"
+	v41 "github.com/atomone-hub/atomone/app/upgrades/v4_1"
 	"github.com/atomone-hub/atomone/client/docs"
 	atomonepost "github.com/atomone-hub/atomone/post"
 )
@@ -68,7 +68,7 @@ var (
 	// DefaultNodeHome default home directories for the application daemon
 	DefaultNodeHome string
 
-	Upgrades = []upgrades.Upgrade{v4.Upgrade}
+	Upgrades = []upgrades.Upgrade{v41.Upgrade}
 )
 
 var (
diff --git a/app/upgrades/v4_1/constants.go b/app/upgrades/v4_1/constants.go
new file mode 100644
index 00000000..bd812c43
--- /dev/null
+++ b/app/upgrades/v4_1/constants.go
@@ -0,0 +1,20 @@
+package v4_1
+
+import (
+	store "cosmossdk.io/store/types"
+
+	"github.com/atomone-hub/atomone/app/upgrades"
+)
+
+const (
+	// UpgradeName is the on-chain name of the testnet-only v4.1 upgrade.
+	UpgradeName = "v4.1"
+)
+
+var Upgrade = upgrades.Upgrade{
+	UpgradeName:          UpgradeName,
+	CreateUpgradeHandler: CreateUpgradeHandler,
+	// No store changes: this upgrade only initializes the staking
+	// KeyRotationFee param missed by the testnet's v4 run.
+	StoreUpgrades: store.StoreUpgrades{},
+}
diff --git a/app/upgrades/v4_1/upgrades.go b/app/upgrades/v4_1/upgrades.go
new file mode 100644
index 00000000..d0a96175
--- /dev/null
+++ b/app/upgrades/v4_1/upgrades.go
@@ -0,0 +1,55 @@
+package v4_1
+
+import (
+	"context"
+
+	"cosmossdk.io/math"
+	upgradetypes "cosmossdk.io/x/upgrade/types"
+
+	"github.com/cosmos/cosmos-sdk/codec"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/module"
+	stakingkeeper "github.com/cosmos/cosmos-sdk/x/staking/keeper"
+
+	"github.com/atomone-hub/atomone/app/keepers"
+)
+
+// CreateUpgradeHandler returns the upgrade handler for AtomOne v4.1.
+//
+// This is a testnet-only upgrade. The testnet ran the v4 upgrade with a binary
+// (v4.0.0-rc) that predated the consensus pubkey rotation feature, so its v4
+// handler never initialized the staking KeyRotationFee param. Mainnet is
+// unaffected: it runs the v4.0.0 binary whose MigrateStakingParams sets the
+// param during the v4 upgrade. After this upgrade the testnet reaches the same
+// post-v4 state as mainnet.
+//
+// No module consensus version changed between the two binaries, so there are no
+// pending module migrations and RunMigrations is intentionally not called.
+func CreateUpgradeHandler(
+	_ *module.Manager,
+	_ codec.Codec,
+	_ module.Configurator,
+	keepers *keepers.AppKeepers,
+) upgradetypes.UpgradeHandler {
+	return func(ctx context.Context, _ upgradetypes.Plan, vm module.VersionMap) (module.VersionMap, error) {
+		if err := InitKeyRotationFee(ctx, keepers.StakingKeeper); err != nil {
+			return vm, err
+		}
+		return vm, nil
+	}
+}
+
+// InitKeyRotationFee initializes the staking KeyRotationFee param to 100 ATONE,
+// mirroring the value set by v4.MigrateStakingParams so the testnet converges to
+// the same state as mainnet.
+func InitKeyRotationFee(ctx context.Context, stakingKeeper *stakingkeeper.Keeper) error {
+	params, err := stakingKeeper.GetParams(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Initialize the consensus pubkey rotation fee to 100 ATONEs
+	params.KeyRotationFee = sdk.NewCoin(params.BondDenom, math.NewInt(100_000000))
+
+	return stakingKeeper.SetParams(ctx, params)
+}
diff --git a/app/upgrades/v4_1/upgrades_test.go b/app/upgrades/v4_1/upgrades_test.go
new file mode 100644
index 00000000..590ca945
--- /dev/null
+++ b/app/upgrades/v4_1/upgrades_test.go
@@ -0,0 +1,29 @@
+package v4_1_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	cmtproto "github.com/cometbft/cometbft/proto/tendermint/types"
+
+	"cosmossdk.io/math"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/atomone-hub/atomone/app/helpers"
+	v4_1 "github.com/atomone-hub/atomone/app/upgrades/v4_1"
+)
+
+func TestInitKeyRotationFee(t *testing.T) {
+	app := helpers.Setup(t)
+	ctx := app.NewUncachedContext(false, cmtproto.Header{})
+	sk := app.StakingKeeper
+
+	require.NoError(t, v4_1.InitKeyRotationFee(ctx, sk))
+
+	got, err := sk.GetParams(ctx)
+	require.NoError(t, err)
+	require.NoError(t, got.Validate())
+	require.Equal(t, sdk.NewCoin(got.BondDenom, math.NewInt(100_000000)), got.KeyRotationFee)
+}