diff --git a/token-validator/students.go b/token-validator/students.go
index a0dda79..e7ca2bf 100644
--- a/token-validator/students.go
+++ b/token-validator/students.go
@@ -64,6 +64,12 @@ func getStudentByLogin(login string) (s Student, err error) {
 	return
 }
 
+func studentExists(login string) bool {
+	var z int
+	err := DBQueryRow("SELECT 1 FROM students WHERE login=?", login).Scan(&z)
+	return err != nil && z == 1
+}
+
 func NewStudent(login string) (Student, error) {
 	if res, err := DBExec("INSERT INTO students (login, time) VALUES (?, ?)", login, time.Now()); err != nil {
 		return Student{}, err
@@ -114,7 +120,11 @@ func createStudent(_ httprouter.Params, body []byte) (interface{}, error) {
 		return nil, err
 	}
 
-	return NewStudent(strings.TrimSpace(std.Login))
+	if exist, err := getStudentByLogin(strings.TrimSpace(std.Login)); err != nil {
+		return NewStudent(strings.TrimSpace(std.Login))
+	} else {
+		return exist, nil
+	}
 }
 
 func updateStudent(current Student, body []byte) (interface{}, error) {