diff --git a/baseapp/baseapp.go b/baseapp/baseapp.go
index d559340c6..6f99d2361 100644
--- a/baseapp/baseapp.go
+++ b/baseapp/baseapp.go
@@ -297,16 +297,31 @@ func (app *BaseApp) runTx(isCheckTx bool, txBytes []byte, tx sdk.Tx) (result sdk
 	// TODO: override default ante handler w/ custom ante handler.
 
 	// Run the ante handler.
-	ctx, result, abort := app.defaultAnteHandler(ctx, tx)
+	if ctx.IsZero() {
+		panic("why? before")
+	}
+	newCtx, result, abort := app.defaultAnteHandler(ctx, tx)
 	if isCheckTx || abort {
 		return result
 	}
+	if !newCtx.IsZero() {
+		ctx = newCtx
+	}
+
+	// CacheWrap app.msDeliver in case it fails.
+	msCache := app.getMultiStore(isCheckTx).CacheMultiStore()
+	ctx = ctx.WithMultiStore(msCache)
 
 	// Match and run route.
 	msgType := tx.Type()
 	handler := app.router.Route(msgType)
 	result = handler(ctx, tx)
 
+	// If result was successful, write to app.msDeliver or app.msCheck.
+	if result.IsOK() {
+		msCache.Write()
+	}
+
 	return result
 }
 
@@ -335,6 +350,14 @@ func (app *BaseApp) Commit() (res abci.ResponseCommit) {
 //----------------------------------------
 // Misc.
 
+func (app *BaseApp) getMultiStore(isCheckTx bool) sdk.MultiStore {
+	if isCheckTx {
+		return app.msCheck
+	} else {
+		return app.msDeliver
+	}
+}
+
 // Return index of list with validator of same PubKey, or -1 if no match
 func pubKeyIndex(val *abci.Validator, list []*abci.Validator) int {
 	for i, v := range list {
diff --git a/baseapp/baseapp_test.go b/baseapp/baseapp_test.go
index 48105e22d..d851a700e 100644
--- a/baseapp/baseapp_test.go
+++ b/baseapp/baseapp_test.go
@@ -77,7 +77,7 @@ func TestBasic(t *testing.T) {
 		}
 		txBytes := toJSON(tx)
 		res := app.DeliverTx(txBytes)
-		assert.True(t, res.IsOK(), "%#v", res)
+		assert.True(t, res.IsOK(), "%#v\nABCI log: %s", res, res.Log)
 	}
 
 	// Simulate the end of a block.
diff --git a/types/context.go b/types/context.go
index 9a5122c13..f8c8ecc7a 100644
--- a/types/context.go
+++ b/types/context.go
@@ -36,15 +36,19 @@ func NewContext(ms MultiStore, header abci.Header, isCheckTx bool, txBytes []byt
 		pst:     newThePast(),
 		gen:     0,
 	}
-	c = c.withMultiStore(ms)
-	c = c.withBlockHeader(header)
-	c = c.withBlockHeight(header.Height)
-	c = c.withChainID(header.ChainID)
-	c = c.withIsCheckTx(isCheckTx)
-	c = c.withTxBytes(txBytes)
+	c = c.WithMultiStore(ms)
+	c = c.WithBlockHeader(header)
+	c = c.WithBlockHeight(header.Height)
+	c = c.WithChainID(header.ChainID)
+	c = c.WithIsCheckTx(isCheckTx)
+	c = c.WithTxBytes(txBytes)
 	return c
 }
 
+func (c Context) IsZero() bool {
+	return c.Context == nil
+}
+
 //----------------------------------------
 // Getting a value
 
@@ -83,10 +87,6 @@ func (c Context) WithProtoMsg(key interface{}, value proto.Message) Context {
 	return c.withValue(key, value)
 }
 
-func (c Context) WithMultiStore(key StoreKey, ms MultiStore) Context {
-	return c.withValue(key, ms)
-}
-
 func (c Context) WithString(key interface{}, value string) Context {
 	return c.withValue(key, value)
 }
@@ -156,34 +156,28 @@ func (c Context) TxBytes() []byte {
 	return c.Value(contextKeyTxBytes).([]byte)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withMultiStore(ms MultiStore) Context {
+func (c Context) WithMultiStore(ms MultiStore) Context {
 	return c.withValue(contextKeyMultiStore, ms)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withBlockHeader(header abci.Header) Context {
+func (c Context) WithBlockHeader(header abci.Header) Context {
 	var _ proto.Message = &header // for cloning.
 	return c.withValue(contextKeyBlockHeader, header)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withBlockHeight(height int64) Context {
+func (c Context) WithBlockHeight(height int64) Context {
 	return c.withValue(contextKeyBlockHeight, height)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withChainID(chainID string) Context {
+func (c Context) WithChainID(chainID string) Context {
 	return c.withValue(contextKeyChainID, chainID)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withIsCheckTx(isCheckTx bool) Context {
+func (c Context) WithIsCheckTx(isCheckTx bool) Context {
 	return c.withValue(contextKeyIsCheckTx, isCheckTx)
 }
 
-// Unexposed to prevent overriding.
-func (c Context) withTxBytes(txBytes []byte) Context {
+func (c Context) WithTxBytes(txBytes []byte) Context {
 	return c.withValue(contextKeyTxBytes, txBytes)
 }
 
diff --git a/types/handler.go b/types/handler.go
index 93b01d9d9..456da14a2 100644
--- a/types/handler.go
+++ b/types/handler.go
@@ -2,4 +2,5 @@ package types
 
 type Handler func(ctx Context, tx Tx) Result
 
+// If newCtx.IsZero(), ctx is used instead.
 type AnteHandler func(ctx Context, tx Tx) (newCtx Context, result Result, abort bool)
diff --git a/types/result.go b/types/result.go
index 3ce194c25..671cae5ea 100644
--- a/types/result.go
+++ b/types/result.go
@@ -33,3 +33,8 @@ type Result struct {
 	// Tags are used for transaction indexing and pubsub.
 	Tags []cmn.KVPair
 }
+
+// TODO: In the future, more codes may be OK.
+func (res Result) IsOK() bool {
+	return res.Code == CodeOK
+}
diff --git a/x/auth/ante.go b/x/auth/ante.go
index 9ea9aa107..fb54dee66 100644
--- a/x/auth/ante.go
+++ b/x/auth/ante.go
@@ -8,7 +8,7 @@ import (
 func NewAnteHandler(accountMapper sdk.AccountMapper) sdk.AnteHandler {
 	return func(
 		ctx sdk.Context, tx sdk.Tx,
-	) (newCtx sdk.Context, res sdk.Result, abort bool) {
+	) (_ sdk.Context, _ sdk.Result, abort bool) {
 
 		// Deduct the fee from the fee payer.
 		// This is done first because it only