diff --git a/plugins/base/imap.go b/plugins/base/imap.go
index 3e268db..8c2040f 100644
--- a/plugins/base/imap.go
+++ b/plugins/base/imap.go
@@ -239,7 +239,7 @@ func searchMessages(conn *imapclient.Client, mboxName, query string, page int) (
 	}
 	total = len(nums)
 
-	from := page*messagesPerPage
+	from := page * messagesPerPage
 	to := from + messagesPerPage
 	if from >= len(nums) {
 		return nil, total, nil
diff --git a/server.go b/server.go
index 266e582..b20b314 100644
--- a/server.go
+++ b/server.go
@@ -14,6 +14,7 @@ const cookieName = "koushin_session"
 
 // Server holds all the koushin server state.
 type Server struct {
+	renderer *renderer
 	Sessions *SessionManager
 	Plugins  []Plugin
 
@@ -72,6 +73,10 @@ func (s *Server) parseSMTPURL(smtpURL string) error {
 	return nil
 }
 
+func (s *Server) Reload() error {
+	return s.renderer.reload(s.Plugins)
+}
+
 func newServer(imapURL, smtpURL string) (*Server, error) {
 	s := &Server{}
 
@@ -150,8 +155,9 @@ func New(e *echo.Echo, options *Options) (*Server, error) {
 	}
 	s.Plugins = append(s.Plugins, luaPlugins...)
 
-	e.Renderer, err = loadTemplates(e.Logger, options.Theme, s.Plugins)
-	if err != nil {
+	s.renderer = newRenderer(e.Logger, options.Theme)
+	e.Renderer = s.renderer
+	if err := s.renderer.reload(s.Plugins); err != nil {
 		return nil, fmt.Errorf("failed to load templates: %v", err)
 	}
 
diff --git a/template.go b/template.go
index 4b46d84..3502a3b 100644
--- a/template.go
+++ b/template.go
@@ -6,6 +6,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"sync"
 
 	"github.com/labstack/echo/v4"
 )
@@ -77,12 +78,18 @@ func NewBaseRenderData(ctx *Context) *BaseRenderData {
 }
 
 type renderer struct {
-	base         *template.Template
-	themes       map[string]*template.Template
+	logger       echo.Logger
 	defaultTheme string
+
+	mutex  sync.RWMutex
+	base   *template.Template
+	themes map[string]*template.Template
 }
 
 func (r *renderer) Render(w io.Writer, name string, data interface{}, ectx echo.Context) error {
+	r.mutex.RLock()
+	defer r.mutex.RUnlock()
+
 	// ectx is the raw *echo.context, not our own *Context
 	ctx := ectx.Get("context").(*Context)
 
@@ -114,12 +121,12 @@ func loadTheme(name string, base *template.Template) (*template.Template, error)
 	return theme, nil
 }
 
-func loadTemplates(logger echo.Logger, defaultTheme string, plugins []Plugin) (*renderer, error) {
+func (r *renderer) reload(plugins []Plugin) error {
 	base := template.New("")
 
 	for _, p := range plugins {
 		if err := p.LoadTemplate(base); err != nil {
-			return nil, fmt.Errorf("failed to load template for plugin '%v': %v", p.Name(), err)
+			return fmt.Errorf("failed to load template for plugin '%v': %v", p.Name(), err)
 		}
 	}
 
@@ -127,7 +134,7 @@ func loadTemplates(logger echo.Logger, defaultTheme string, plugins []Plugin) (*
 
 	files, err := ioutil.ReadDir(themesDir)
 	if err != nil && !os.IsNotExist(err) {
-		return nil, err
+		return err
 	}
 
 	for _, fi := range files {
@@ -135,22 +142,29 @@ func loadTemplates(logger echo.Logger, defaultTheme string, plugins []Plugin) (*
 			continue
 		}
 
-		logger.Printf("Loading theme '%v'", fi.Name())
+		r.logger.Printf("Loading theme '%v'", fi.Name())
 		var err error
 		if themes[fi.Name()], err = loadTheme(fi.Name(), base); err != nil {
-			return nil, fmt.Errorf("failed to load theme '%v': %v", fi.Name(), err)
+			return fmt.Errorf("failed to load theme '%v': %v", fi.Name(), err)
 		}
 	}
 
-	if defaultTheme != "" {
-		if _, ok := themes[defaultTheme]; !ok {
-			return nil, fmt.Errorf("failed to find default theme '%v'", defaultTheme)
+	if r.defaultTheme != "" {
+		if _, ok := themes[r.defaultTheme]; !ok {
+			return fmt.Errorf("failed to find default theme '%v'", r.defaultTheme)
 		}
 	}
 
+	r.mutex.Lock()
+	r.base = base
+	r.themes = themes
+	r.mutex.Unlock()
+	return nil
+}
+
+func newRenderer(logger echo.Logger, defaultTheme string) *renderer {
 	return &renderer{
-		base:         base,
-		themes:       themes,
+		logger:       logger,
 		defaultTheme: defaultTheme,
-	}, nil
+	}
 }