diff --git a/server/server.go b/server/server.go
index ead52aa..4d1caad 100644
--- a/server/server.go
+++ b/server/server.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"text/template"
+	"time"
 
 	"git.ctrlz.es/mgdelacroix/birthdaybot/model"
 	"git.ctrlz.es/mgdelacroix/birthdaybot/notification"
@@ -94,6 +95,12 @@ func New(options ...Option) (*Server, error) {
 		if err != nil {
 			return nil, fmt.Errorf("cannot parse template file %q: %w", srv.Config.Birthdays.Template, err)
 		}
+
+		srv.tmpl.Funcs(template.FuncMap{
+			"GetYearsOld": func(yearOfBirth int) int {
+				return time.Now().Year() - yearOfBirth
+			},
+		})
 	}
 
 	return srv, nil