diff --git a/manager.go b/manager.go
index b2041d0..a24334b 100644
--- a/manager.go
+++ b/manager.go
@@ -15,6 +15,15 @@ const (
 	idLen       = 40
 )
 
+var (
+	// ErrUnauthorized is returned when no valid session is found.
+	ErrUnauthorized = errors.New("unauthorized")
+
+	// ErrNotOwner is returned when session's status is being modified
+	// not by its owner.
+	ErrNotOwner = errors.New("session can be managed only by its owner")
+)
+
 // Manager holds the data needed to properly create sessions
 // and set them in http responses, extract them from http requests,
 // validate them and directly communicate with the store.
@@ -211,13 +220,16 @@ func (m *Manager) Clone(opts ...setter) *Manager {
 // the store and sets the proper values of the cookie.
 func (m *Manager) Init(w http.ResponseWriter, r *http.Request, key string) error {
 	s := m.newSession(r, key)
-	if s.ExpiresAt.After(time.Time{}) {
-		if err := m.store.Create(r.Context(), s); err != nil {
-			return err
-		}
+	exp := s.ExpiresAt
+	if s.ExpiresAt.IsZero() {
+		s.ExpiresAt = time.Now().Add(time.Hour * 24) // for temporary sessions
+	}
+
+	if err := m.store.Create(r.Context(), s); err != nil {
+		return err
 	}
 
-	m.setCookie(w, s.ExpiresAt, s.ID)
+	m.setCookie(w, exp, s.ID)
 	return nil
 }
 
@@ -265,12 +277,12 @@ func (m *Manager) wrap(rej func(error) http.Handler, next http.Handler) http.Han
 		}
 
 		if !ok {
-			rej(errors.New("unauthorized")).ServeHTTP(w, r)
+			rej(ErrUnauthorized).ServeHTTP(w, r)
 			return
 		}
 
 		if m.validate && !s.IsValid(r) {
-			rej(errors.New("unauthorized")).ServeHTTP(w, r)
+			rej(ErrUnauthorized).ServeHTTP(w, r)
 			return
 		}
 
@@ -320,7 +332,7 @@ func (m *Manager) RevokeByIDExt(ctx context.Context, id string) error {
 	}
 
 	if s2.UserKey != s1.UserKey {
-		return errors.New("session can be revoked only by its owner")
+		return ErrNotOwner
 	}
 
 	return m.store.DeleteByID(ctx, id)
diff --git a/manager_test.go b/manager_test.go
index 335dc04..9954122 100644
--- a/manager_test.go
+++ b/manager_test.go
@@ -244,16 +244,28 @@ func TestInit(t *testing.T) {
 		}
 	}
 
-	wasCreateCalled := func(count int, key string) check {
+	wasCreateCalled := func(count int, key string, t1, t2 time.Time) check {
 		return func(t *testing.T, s *StoreMock, _ *httptest.ResponseRecorder, _ error) {
 			ff := s.CreateCalls()
 			if len(ff) != count {
 				t.Errorf("want %d, got %d", count, len(ff))
 			}
 
-			if len(ff) > 0 && ff[0].S.UserKey != key {
+			if len(ff) == 0 {
+				return
+			}
+
+			if ff[0].S.UserKey != key {
 				t.Errorf("want %q, got %q", key, ff[0].S.UserKey)
 			}
+
+			if !ff[0].S.ExpiresAt.After(t1) {
+				t.Errorf("want after %s, got %s", t1.String(), ff[0].S.ExpiresAt.String())
+			}
+
+			if !ff[0].S.ExpiresAt.Before(t2) {
+				t.Errorf("want before %s, got %s", t2.String(), ff[0].S.ExpiresAt.String())
+			}
 		}
 	}
 
@@ -274,28 +286,30 @@ func TestInit(t *testing.T) {
 	}{
 		"Error returned by store.Create": {
 			Store:     storeStub(errors.New("error")),
-			ExpiresIn: time.Hour,
+			ExpiresIn: time.Hour * 24 * 30,
 			Checks: checks(
 				hasErr(true),
 				hasCookie(false),
-				wasCreateCalled(1, key),
+				wasCreateCalled(1, key, time.Now().Add(time.Hour*24),
+					time.Now().Add(time.Hour*24*30+time.Second)),
 			),
 		},
-		"Successful init without expiration field": {
+		"Successful temporary session init": {
 			Store: storeStub(nil),
 			Checks: checks(
 				hasErr(false),
 				hasCookie(true),
-				wasCreateCalled(0, ""),
+				wasCreateCalled(1, key, time.Time{}, time.Now().Add(time.Hour*24+time.Second)),
 			),
 		},
-		"Successful init": {
+		"Successful permanent session init": {
 			Store:     storeStub(nil),
-			ExpiresIn: time.Hour,
+			ExpiresIn: time.Hour * 24 * 30,
 			Checks: checks(
 				hasErr(false),
 				hasCookie(true),
-				wasCreateCalled(1, key),
+				wasCreateCalled(1, key, time.Now().Add(time.Hour*24),
+					time.Now().Add(time.Hour*24*30+time.Second)),
 			),
 		},
 	}