diff --git a/mempool/mempool_test.go b/mempool/mempool_test.go
index ad655c6d..16dd656f 100644
--- a/mempool/mempool_test.go
+++ b/mempool/mempool_test.go
@@ -75,9 +75,9 @@ func TestSerialReap(t *testing.T) {
 					res.Code, res.Data, res.Log)
 			}
 		}
-		hash, log := appConnCon.Commit()
-		if len(hash) != 8 {
-			t.Errorf("Error committing. Hash:%X log:%v", hash, log)
+		res := appConnCon.Commit()
+		if len(res.Data) != 8 {
+			t.Errorf("Error committing. Hash:%X log:%v", res.Data, res.Log)
 		}
 	}
 
diff --git a/node/node.go b/node/node.go
index 8beafcee..79e4b9c3 100644
--- a/node/node.go
+++ b/node/node.go
@@ -258,12 +258,12 @@ func getProxyApp(addr string, hash []byte) (proxyAppConn proxy.AppConn) {
 	}
 
 	// Check the hash
-	currentHash, _, err := proxyAppConn.CommitSync()
-	if err != nil {
-		PanicCrisis(Fmt("Error in getting proxyAppConn hash: %v", err))
+	res := proxyAppConn.CommitSync()
+	if res.IsErr() {
+		PanicCrisis(Fmt("Error in getting proxyAppConn hash: %v", res))
 	}
-	if !bytes.Equal(hash, currentHash) {
-		PanicCrisis(Fmt("ProxyApp hash does not match.  Expected %X, got %X", hash, currentHash))
+	if !bytes.Equal(hash, res.Data) {
+		PanicCrisis(Fmt("ProxyApp hash does not match.  Expected %X, got %X", hash, res.Data))
 	}
 
 	return proxyAppConn
diff --git a/proxy/app_conn.go b/proxy/app_conn.go
index b371f6d2..7311a07b 100644
--- a/proxy/app_conn.go
+++ b/proxy/app_conn.go
@@ -18,7 +18,7 @@ type AppConn interface {
 
 	InfoSync() (info string, err error)
 	FlushSync() error
-	CommitSync() (hash []byte, log string, err error)
+	CommitSync() (res tmsp.Result)
 	InitChainSync(validators []*tmsp.Validator) (err error)
 	EndBlockSync(height uint64) (changedValidators []*tmsp.Validator, err error)
 }
diff --git a/proxy/local_app_conn.go b/proxy/local_app_conn.go
index 59ae33b5..c2cab071 100644
--- a/proxy/local_app_conn.go
+++ b/proxy/local_app_conn.go
@@ -74,11 +74,11 @@ func (app *localAppConn) CheckTxAsync(tx []byte) *tmspcli.ReqRes {
 
 func (app *localAppConn) CommitAsync() *tmspcli.ReqRes {
 	app.mtx.Lock()
-	hash, log := app.Application.Commit()
+	res := app.Application.Commit()
 	app.mtx.Unlock()
 	return app.callback(
 		tmsp.RequestCommit(),
-		tmsp.ResponseCommit(hash, log),
+		tmsp.ResponseCommit(res.Code, res.Data, res.Log),
 	)
 }
 
@@ -93,11 +93,11 @@ func (app *localAppConn) FlushSync() error {
 	return nil
 }
 
-func (app *localAppConn) CommitSync() (hash []byte, log string, err error) {
+func (app *localAppConn) CommitSync() (res tmsp.Result) {
 	app.mtx.Lock()
-	hash, log = app.Application.Commit()
+	res = app.Application.Commit()
 	app.mtx.Unlock()
-	return hash, log, nil
+	return res
 }
 
 func (app *localAppConn) InitChainSync(validators []*tmsp.Validator) (err error) {
diff --git a/state/execution.go b/state/execution.go
index 199cc805..404efa26 100644
--- a/state/execution.go
+++ b/state/execution.go
@@ -95,18 +95,18 @@ func (s *State) execBlockOnProxyApp(evsw *events.EventSwitch, proxyAppConn proxy
 	log.Info("TODO: Do something with changedValidators", changedValidators)
 
 	// Commit block, get hash back
-	hash, logStr, err := proxyAppConn.CommitSync()
-	if err != nil {
-		log.Warn("Error in proxyAppConn.CommitSync", "error", err)
-		return err
+	res := proxyAppConn.CommitSync()
+	if res.IsErr() {
+		log.Warn("Error in proxyAppConn.CommitSync", "error", res)
+		return res
 	}
-	if logStr != "" {
-		log.Debug("Commit.Log: " + logStr)
+	if res.Log != "" {
+		log.Debug("Commit.Log: " + res.Log)
 	}
 	log.Info(Fmt("ExecBlock got %v valid txs and %v invalid txs", validTxs, invalidTxs))
 
 	// Set the state's new AppHash
-	s.AppHash = hash
+	s.AppHash = res.Data
 
 	return nil
 }