diff --git a/libadlin/db.go b/libadlin/db.go
index 5fafcc9..cfa149b 100644
--- a/libadlin/db.go
+++ b/libadlin/db.go
@@ -114,8 +114,10 @@ CREATE TABLE IF NOT EXISTS student_challenge_errors(
 	if _, err := db.Exec(`
 CREATE TABLE IF NOT EXISTS student_pong(
   id_student INTEGER NOT NULL,
-  time TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  last TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  count INTEGER UNSIGNED DEFAULT 1,
   state BOOLEAN NOT NULL DEFAULT 0,
+  CONSTRAINT one_pong UNIQUE (id_student,state),
   FOREIGN KEY(id_student) REFERENCES students(id_student)
 ) DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
 `); err != nil {
diff --git a/libadlin/ping.go b/libadlin/ping.go
index a93fc9c..9926a87 100644
--- a/libadlin/ping.go
+++ b/libadlin/ping.go
@@ -6,18 +6,19 @@ import (
 
 type Pong struct {
 	Date  time.Time
+	Count uint
 	State bool
 }
 
 func (s *Student) LastPongs() (pongs []*Pong, err error) {
-	if rows, errr := DBQuery("SELECT time, state FROM student_pong WHERE id_student = ? ORDER BY time DESC", s.Id); errr != nil {
+	if rows, errr := DBQuery("SELECT last, count, state FROM student_pong WHERE id_student = ? ORDER BY last DESC", s.Id); errr != nil {
 		return nil, errr
 	} else {
 		defer rows.Close()
 
 		for rows.Next() {
 			p := &Pong{}
-			if err = rows.Scan(&p.Date, &p.State); err != nil {
+			if err = rows.Scan(&p.Date, &p.Count, &p.State); err != nil {
 				return
 			}
 			pongs = append(pongs, p)
@@ -31,6 +32,9 @@ func (s *Student) LastPongs() (pongs []*Pong, err error) {
 }
 
 func (s *Student) OnPong(state bool) (err error) {
-	_, err = DBExec("INSERT INTO student_pong (id_student, time, state) VALUES (?, ?, ?)", s.Id, time.Now(), state)
+	_, err = DBExec("INSERT INTO student_pong (id_student, last, state) VALUES (?, ?, ?)", s.Id, time.Now(), state)
+	if err != nil {
+		_, err = DBExec("UPDATE student_pong SET last = CURRENT_TIMESTAMP, count = count + 1 WHERE id_student = ? AND state = ?", s.Id, state)
+	}
 	return
 }