diff --git a/x/distribution/keeper/hooks.go b/x/distribution/keeper/hooks.go
index 721a26db1d..6031d056b5 100644
--- a/x/distribution/keeper/hooks.go
+++ b/x/distribution/keeper/hooks.go
@@ -14,16 +14,18 @@ func (k Keeper) onValidatorCreated(ctx sdk.Context, addr sdk.ValAddress) {
 	vdi := types.ValidatorDistInfo{
 		OperatorAddr:            addr,
 		FeePoolWithdrawalHeight: height,
-		Pool:           types.DecCoins{},
-		PoolCommission: types.DecCoins{},
-		DelAccum:       types.NewTotalAccum(height),
+		Pool:                    types.DecCoins{},
+		PoolCommission:          types.DecCoins{},
+		DelAccum:                types.NewTotalAccum(height),
 	}
 	k.SetValidatorDistInfo(ctx, vdi)
 }
 
 // Withdrawal all validator rewards
 func (k Keeper) onValidatorCommissionChange(ctx sdk.Context, addr sdk.ValAddress) {
-	k.WithdrawValidatorRewardsAll(ctx, addr)
+	if err := k.WithdrawValidatorRewardsAll(ctx, addr); err != nil {
+		panic(err)
+	}
 }
 
 // Withdrawal all validator distribution rewards and cleanup the distribution record
@@ -50,7 +52,9 @@ func (k Keeper) onDelegationCreated(ctx sdk.Context, delAddr sdk.AccAddress,
 func (k Keeper) onDelegationSharesModified(ctx sdk.Context, delAddr sdk.AccAddress,
 	valAddr sdk.ValAddress) {
 
-	k.WithdrawDelegationReward(ctx, delAddr, valAddr)
+	if err := k.WithdrawDelegationReward(ctx, delAddr, valAddr); err != nil {
+		panic(err)
+	}
 }
 
 // Withdrawal all validator distribution rewards and cleanup the distribution record
diff --git a/x/distribution/keeper/validator.go b/x/distribution/keeper/validator.go
index bbc2a732ed..8b38b0f6a0 100644
--- a/x/distribution/keeper/validator.go
+++ b/x/distribution/keeper/validator.go
@@ -74,6 +74,7 @@ func (k Keeper) WithdrawValidatorRewardsAll(ctx sdk.Context, operatorAddr sdk.Va
 	return nil
 }
 
+// iterate over all the validator distribution infos (inefficient, just used to check invariants)
 func (k Keeper) IterateValidatorDistInfos(ctx sdk.Context, fn func(index int64, distInfo types.ValidatorDistInfo) (stop bool)) {
 	store := ctx.KVStore(k.storeKey)
 	iter := sdk.KVStorePrefixIterator(store, ValidatorDistInfoKey)
diff --git a/x/stake/simulation/sim_test.go b/x/stake/simulation/sim_test.go
index 6aa7801139..207f42e616 100644
--- a/x/stake/simulation/sim_test.go
+++ b/x/stake/simulation/sim_test.go
@@ -8,7 +8,9 @@ import (
 	abci "github.com/tendermint/tendermint/abci/types"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/auth"
 	"github.com/cosmos/cosmos-sdk/x/bank"
+	"github.com/cosmos/cosmos-sdk/x/distribution"
 	"github.com/cosmos/cosmos-sdk/x/mock"
 	"github.com/cosmos/cosmos-sdk/x/mock/simulation"
 	"github.com/cosmos/cosmos-sdk/x/params"
@@ -22,13 +24,17 @@ func TestStakeWithRandomMessages(t *testing.T) {
 	bank.RegisterCodec(mapp.Cdc)
 	mapper := mapp.AccountMapper
 	bankKeeper := bank.NewBaseKeeper(mapper)
+	feeKey := sdk.NewKVStoreKey("fee")
 	stakeKey := sdk.NewKVStoreKey("stake")
 	stakeTKey := sdk.NewTransientStoreKey("transient_stake")
 	paramsKey := sdk.NewKVStoreKey("params")
 	paramsTKey := sdk.NewTransientStoreKey("transient_params")
+	distrKey := sdk.NewKVStoreKey("distr")
 
-	paramstore := params.NewKeeper(mapp.Cdc, paramsKey, paramsTKey).Subspace(stake.DefaultParamspace)
-	stakeKeeper := stake.NewKeeper(mapp.Cdc, stakeKey, stakeTKey, bankKeeper, paramstore, stake.DefaultCodespace)
+	feeCollectionKeeper := auth.NewFeeCollectionKeeper(mapp.Cdc, feeKey)
+	paramstore := params.NewKeeper(mapp.Cdc, paramsKey, paramsTKey)
+	stakeKeeper := stake.NewKeeper(mapp.Cdc, stakeKey, stakeTKey, bankKeeper, paramstore.Subspace(stake.DefaultParamspace), stake.DefaultCodespace)
+	distrKeeper := distribution.NewKeeper(mapp.Cdc, distrKey, paramstore.Subspace(distribution.DefaultParamspace), bankKeeper, stakeKeeper, feeCollectionKeeper, distribution.DefaultCodespace)
 	mapp.Router().AddRoute("stake", stake.NewHandler(stakeKeeper))
 	mapp.SetEndBlocker(func(ctx sdk.Context, req abci.RequestEndBlock) abci.ResponseEndBlock {
 		validatorUpdates := stake.EndBlocker(ctx, stakeKeeper)
@@ -58,7 +64,7 @@ func TestStakeWithRandomMessages(t *testing.T) {
 		}, []simulation.RandSetup{
 			Setup(mapp, stakeKeeper),
 		}, []simulation.Invariant{
-			AllInvariants(bankKeeper, stakeKeeper, mapp.AccountMapper),
+			AllInvariants(bankKeeper, stakeKeeper, distrKeeper, mapp.AccountMapper),
 		}, 10, 100,
 		false,
 	)