diff --git a/app/controllers/gorp.go b/app/controllers/gorp.go
index 6744306..5678fe4 100644
--- a/app/controllers/gorp.go
+++ b/app/controllers/gorp.go
@@ -25,9 +25,15 @@ func InitDB() {
 	appTableMap := Dbm.AddTableWithName(models.App{}, "app")
 	appTableMap.SetKeys(true, "Id")
 	appTableMap.ColMap("ApiToken").SetUnique(true)
+	appTableMap.ColMap("FileId").SetUnique(true)
 
 	bundleTableMap := Dbm.AddTableWithName(models.Bundle{}, "bundle")
 	bundleTableMap.SetKeys(true, "Id")
+	bundleTableMap.ColMap("FileId").SetUnique(true)
+
+	revisionTableMap := Dbm.AddTableWithName(models.Revision{}, "revision")
+	revisionTableMap.SetKeys(true, "Id")
+	revisionTableMap.SetUniqueTogether("app_id", "platform_type", "bundle_version")
 
 	authorityTableMap := Dbm.AddTableWithName(models.Authority{}, "authority")
 	authorityTableMap.SetKeys(true, "Id")
@@ -39,7 +45,10 @@ func InitDB() {
 	auditTableMap.SetKeys(true, "Id")
 
 	Dbm.TraceOn("[gorp]", revel.INFO)
-	Dbm.CreateTablesIfNotExists()
+	err := Dbm.CreateTablesIfNotExists()
+	if err != nil {
+		panic(err)
+	}
 }
 
 func getDbm() *gorp.DbMap {
diff --git a/app/models/app.go b/app/models/app.go
index ae87601..76f1fc6 100644
--- a/app/models/app.go
+++ b/app/models/app.go
@@ -3,6 +3,7 @@ package models
 import (
 	"crypto/hmac"
 	"crypto/sha256"
+	"database/sql"
 	"encoding/hex"
 	"fmt"
 	"strings"
@@ -77,13 +78,42 @@ func (app *App) Authorities(txn gorp.SqlExecutor) ([]*Authority, error) {
 	return authorities, nil
 }
 
-func (app *App) GetMaxRevisionByBundleVersion(txn gorp.SqlExecutor, bundleVersion string) (int, error) {
-	revision, err := txn.SelectInt(
-		"SELECT IFNULL(MAX(revision), 0) FROM bundle WHERE app_id = ? AND bundle_version = ?",
+func (app *App) IncrementRevision(txn gorp.SqlExecutor, platformType BundlePlatformType, bundleVersion string) (int, error) {
+	revision, err := GetMaxRevision(
+		txn,
 		app.Id,
+		platformType,
 		bundleVersion,
 	)
-	return int(revision), err
+
+	if err == sql.ErrNoRows {
+		var maxRevision int64
+		maxRevision, err = txn.SelectInt(
+			"SELECT IFNULL(MAX(revision), 0) FROM bundle WHERE app_id = ? AND platform_type = ? AND bundle_version = ?",
+			app.Id,
+			platformType,
+			bundleVersion,
+		)
+		if err != nil {
+			return 0, err
+		}
+		maxRevision++
+		revision = &Revision{
+			AppId:         app.Id,
+			PlatformType:  platformType,
+			BundleVersion: bundleVersion,
+			MaxRevision:   int(maxRevision),
+		}
+		err = revision.Save(txn)
+	} else if err == nil {
+		revision.MaxRevision++
+		err = revision.Update(txn)
+	}
+
+	if err != nil {
+		return 0, err
+	}
+	return revision.MaxRevision, err
 }
 
 func NewToken() string {
@@ -227,13 +257,13 @@ func (app *App) CreateBundle(dbm *gorp.DbMap, s *GoogleService, bundle *Bundle)
 
 	// increment revision number & save application information
 	err = Transact(dbm, func(txn gorp.SqlExecutor) error {
-		maxRevision, err := app.GetMaxRevisionByBundleVersion(txn, bundleInfo.Version)
+		nextRevision, err := app.IncrementRevision(txn, bundle.PlatformType, bundleInfo.Version)
 		if err != nil {
 			return err
 		}
-		bundle.Revision = maxRevision + 1
+		bundle.Revision = nextRevision
 		bundle.FileName = bundle.BuildFileName()
-		return bundle.Save(txn)
+		return nil
 	})
 	if err != nil {
 		panic(err)
@@ -249,7 +279,7 @@ func (app *App) CreateBundle(dbm *gorp.DbMap, s *GoogleService, bundle *Bundle)
 	// update FileId
 	bundle.FileId = driveFile.Id
 	return Transact(dbm, func(txn gorp.SqlExecutor) error {
-		return bundle.Update(txn)
+		return bundle.Save(txn)
 	})
 }
 
diff --git a/app/models/revision.go b/app/models/revision.go
new file mode 100644
index 0000000..3a82e39
--- /dev/null
+++ b/app/models/revision.go
@@ -0,0 +1,37 @@
+package models
+
+import (
+	"github.com/coopernurse/gorp"
+)
+
+type Revision struct {
+	Id            int                `db:"id"`
+	AppId         int                `db:"app_id"`
+	PlatformType  BundlePlatformType `db:"platform_type"`
+	BundleVersion string             `db:"bundle_version"`
+	MaxRevision   int                `db:"max_revision"`
+}
+
+func GetMaxRevision(txn gorp.SqlExecutor, appId int, platformType BundlePlatformType, bundleVersion string) (*Revision, error) {
+	var revision Revision
+	err := txn.SelectOne(
+		&revision,
+		"SELECT * FROM revision WHERE app_id = ? AND platform_type = ? AND bundle_version = ?",
+		appId,
+		platformType,
+		bundleVersion,
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &revision, nil
+}
+
+func (r *Revision) Save(txn gorp.SqlExecutor) error {
+	return txn.Insert(r)
+}
+
+func (r *Revision) Update(txn gorp.SqlExecutor) error {
+	_, err := txn.Update(r)
+	return err
+}