diff --git a/README.md b/README.md
index 99d070ba..d378e6ab 100644
--- a/README.md
+++ b/README.md
@@ -236,7 +236,7 @@ To install Mercure in a [Kubernetes](https://kubernetes.io) cluster, use the off
 * `COMPRESS`: set to `0` to disable HTTP compression support (default to enabled)
 * `CORS_ALLOWED_ORIGINS`: a comma separated list of allowed CORS origins, can be `*` for all
 * `DB_PATH`: the path of the [bbolt](https://github.com/etcd-io/bbolt) database (default to `updates.db` in the current directory)
-* `DEBUG`: set to `1` to enable the debug mode (prints recovery stack traces)
+* `DEBUG`: set to `1` to enable the debug mode, **dangerous, don't enable in production** (logs updates' content, why an update is not send to a specific subscriber and recovery stack traces)
 * `DEMO`: set to `1` to enable the demo mode (automatically enabled when `DEBUG=1`)
 * `HEARTBEAT_INTERVAL`: interval between heartbeats (useful with some proxies, and old browsers, default to `15s`, set to `0s` to disable)
 * `HISTORY_SIZE`: size of the history (to retrieve lost messages using the `Last-Event-ID` header), set to `0` to never remove old events (default)
diff --git a/hub/history_test.go b/hub/history_test.go
index 23a4e08d..1851f882 100644
--- a/hub/history_test.go
+++ b/hub/history_test.go
@@ -20,7 +20,7 @@ func TestBoltHistory(t *testing.T) {
 
 	count := 0
 	assert.Nil(t, h.FindFor(
-		NewSubscriber(false, map[string]struct{}{}, []string{}, []*uritemplate.Template{}, ""),
+		NewSubscriber(false, map[string]struct{}{}, []string{}, []string{}, []*uritemplate.Template{}, ""),
 		func(*Update) bool {
 			count++
 			return true
@@ -55,7 +55,7 @@ func TestBoltHistory(t *testing.T) {
 	}))
 
 	h.FindFor(
-		NewSubscriber(false, map[string]struct{}{"foo": {}}, []string{"http://example.com/alt/3"}, []*uritemplate.Template{}, "first"),
+		NewSubscriber(false, map[string]struct{}{"foo": {}}, []string{"http://example.com/alt/3"}, []string{"http://example.com/alt/3"}, []*uritemplate.Template{}, "first"),
 		func(u *Update) bool {
 			count++
 
diff --git a/hub/log.go b/hub/log.go
new file mode 100644
index 00000000..9c6d90d7
--- /dev/null
+++ b/hub/log.go
@@ -0,0 +1,29 @@
+package hub
+
+import (
+	"net/http"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func (h *Hub) createLogFields(r *http.Request, u *Update, s *Subscriber) log.Fields {
+	fields := log.Fields{
+		"remote_addr":    r.RemoteAddr,
+		"event_id":       u.ID,
+		"event_type":     u.Type,
+		"event_retry":    u.Retry,
+		"update_topics":  u.Topics,
+		"update_targets": u.Targets,
+	}
+	if h.options.Debug {
+		fields["update_data"] = u.Data
+	}
+
+	if s != nil {
+		fields["last_event_id"] = s.LastEventID
+		fields["subscriber_topics"] = s.Topics
+		fields["subscriber_targets"] = s.Targets
+	}
+
+	return fields
+}
diff --git a/hub/publish.go b/hub/publish.go
index cd30bf14..f6121250 100644
--- a/hub/publish.go
+++ b/hub/publish.go
@@ -96,5 +96,5 @@ func (h *Hub) PublishHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	io.WriteString(w, u.ID)
-	log.WithFields(log.Fields{"remote_addr": r.RemoteAddr, "event_id": u.ID}).Info("Update published")
+	log.WithFields(h.createLogFields(r, u, nil)).Info("Update published")
 }
diff --git a/hub/subscribe.go b/hub/subscribe.go
index 973d1b61..a109396f 100644
--- a/hub/subscribe.go
+++ b/hub/subscribe.go
@@ -30,7 +30,7 @@ func (h *Hub) SubscribeHandler(w http.ResponseWriter, r *http.Request) {
 			if !open {
 				return
 			}
-			publish(serializedUpdate, subscriber, w, r)
+			h.publish(serializedUpdate, subscriber, w, r)
 
 			continue
 		}
@@ -40,7 +40,7 @@ func (h *Hub) SubscribeHandler(w http.ResponseWriter, r *http.Request) {
 			if !open {
 				return
 			}
-			publish(serializedUpdate, subscriber, w, r)
+			h.publish(serializedUpdate, subscriber, w, r)
 
 		case <-time.After(h.options.HeartbeatInterval):
 			// Send a SSE comment as a heartbeat, to prevent issues with some proxies and old browsers
@@ -52,10 +52,16 @@ func (h *Hub) SubscribeHandler(w http.ResponseWriter, r *http.Request) {
 
 // initSubscription initializes the connection
 func (h *Hub) initSubscription(w http.ResponseWriter, r *http.Request) (*Subscriber, chan *serializedUpdate, bool) {
+	fields := log.Fields{"remote_addr": r.RemoteAddr}
+
 	claims, err := authorize(r, h.options.SubscriberJWTKey, nil)
+	if h.options.Debug && claims != nil {
+		fields["target"] = claims.Mercure.Subscribe
+	}
+
 	if err != nil || (claims == nil && !h.options.AllowAnonymous) {
 		http.Error(w, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
-		log.WithFields(log.Fields{"remote_addr": r.RemoteAddr}).Info(err)
+		log.WithFields(fields).Info(err)
 		return nil, nil, false
 	}
 
@@ -64,6 +70,7 @@ func (h *Hub) initSubscription(w http.ResponseWriter, r *http.Request) (*Subscri
 		http.Error(w, "Missing \"topic\" parameter.", http.StatusBadRequest)
 		return nil, nil, false
 	}
+	fields["subscriber_topics"] = topics
 
 	var rawTopics = make([]string, 0, len(topics))
 	var templateTopics = make([]*uritemplate.Template, 0, len(topics))
@@ -75,11 +82,11 @@ func (h *Hub) initSubscription(w http.ResponseWriter, r *http.Request) (*Subscri
 		}
 	}
 
-	log.WithFields(log.Fields{"remote_addr": r.RemoteAddr}).Info("New subscriber")
 	sendHeaders(w)
+	log.WithFields(fields).Info("New subscriber")
 
 	authorizedAlltargets, authorizedTargets := authorizedTargets(claims, false)
-	subscriber := NewSubscriber(authorizedAlltargets, authorizedTargets, rawTopics, templateTopics, retrieveLastEventID(r))
+	subscriber := NewSubscriber(authorizedAlltargets, authorizedTargets, topics, rawTopics, templateTopics, retrieveLastEventID(r))
 
 	if subscriber.LastEventID != "" {
 		h.sendMissedEvents(w, r, subscriber)
@@ -97,7 +104,7 @@ func (h *Hub) initSubscription(w http.ResponseWriter, r *http.Request) (*Subscri
 	go func() {
 		<-notify
 		h.removedSubscribers <- updateChan
-		log.WithFields(log.Fields{"remote_addr": r.RemoteAddr}).Info("Subscriber disconnected")
+		log.WithFields(fields).Info("Subscriber disconnected")
 	}()
 
 	return subscriber, updateChan, true
@@ -160,11 +167,8 @@ func (h *Hub) sendMissedEvents(w http.ResponseWriter, r *http.Request, s *Subscr
 	if err := h.history.FindFor(s, func(u *Update) bool {
 		fmt.Fprint(w, u.String())
 		f.Flush()
-		log.WithFields(log.Fields{
-			"event_id":      u.ID,
-			"last_event_id": s.LastEventID,
-			"remote_addr":   r.RemoteAddr,
-		}).Info("Event sent")
+		log.WithFields(h.createLogFields(r, u, s)).Info("Event sent")
+
 		return true
 	}); err != nil {
 		panic(err)
@@ -172,18 +176,22 @@ func (h *Hub) sendMissedEvents(w http.ResponseWriter, r *http.Request, s *Subscr
 }
 
 // publish sends the update to the client, if authorized
-func publish(serializedUpdate *serializedUpdate, subscriber *Subscriber, w http.ResponseWriter, r *http.Request) {
-	// Check authorization
-	if !subscriber.CanReceive(serializedUpdate.Update) {
+func (h *Hub) publish(serializedUpdate *serializedUpdate, subscriber *Subscriber, w http.ResponseWriter, r *http.Request) {
+	fields := h.createLogFields(r, serializedUpdate.Update, subscriber)
+
+	if !subscriber.IsAuthorized(serializedUpdate.Update) {
+		log.WithFields(fields).Debug("Subscriber not authorized to receive this update (no targets matching)")
+		return
+	}
+
+	if !subscriber.IsSubscribed(serializedUpdate.Update) {
+		log.WithFields(fields).Debug("Subscriber has not subscribed to this update (no topics matching)")
 		return
 	}
 
 	fmt.Fprint(w, serializedUpdate.event)
-	log.WithFields(log.Fields{
-		"event_id":    serializedUpdate.ID,
-		"remote_addr": r.RemoteAddr,
-	}).Info("Event sent")
 	w.(http.Flusher).Flush()
+	log.WithFields(fields).Info("Event sent")
 }
 
 // cleanup removes unused uritemplate.Template instances from memory
diff --git a/hub/subscribe_test.go b/hub/subscribe_test.go
index 7b07e268..29d50d2c 100644
--- a/hub/subscribe_test.go
+++ b/hub/subscribe_test.go
@@ -120,7 +120,6 @@ func testSubscribe(numberOfSubscribers int, t *testing.T) {
 			hub.subscribers.RUnlock()
 
 			if !ready {
-				//time.Sleep(time.Millisecond)
 				continue
 			}
 
@@ -200,6 +199,7 @@ func TestUnsubscribe(t *testing.T) {
 
 func TestSubscribeTarget(t *testing.T) {
 	hub := createDummy()
+	hub.options.Debug = true
 	hub.Start()
 
 	go func() {
diff --git a/hub/subscriber.go b/hub/subscriber.go
index 0412de92..d719d2b0 100644
--- a/hub/subscriber.go
+++ b/hub/subscriber.go
@@ -15,6 +15,7 @@ type subscribers struct {
 type Subscriber struct {
 	AllTargets     bool
 	Targets        map[string]struct{}
+	Topics         []string
 	RawTopics      []string
 	TemplateTopics []*uritemplate.Template
 	LastEventID    string
@@ -22,17 +23,18 @@ type Subscriber struct {
 }
 
 // NewSubscriber creates a subscriber
-func NewSubscriber(allTargets bool, targets map[string]struct{}, rawTopics []string, templateTopics []*uritemplate.Template, lastEventID string) *Subscriber {
-	return &Subscriber{allTargets, targets, rawTopics, templateTopics, lastEventID, make(map[string]bool)}
+func NewSubscriber(allTargets bool, targets map[string]struct{}, topics []string, rawTopics []string, templateTopics []*uritemplate.Template, lastEventID string) *Subscriber {
+	return &Subscriber{allTargets, targets, topics, rawTopics, templateTopics, lastEventID, make(map[string]bool)}
 }
 
 // CanReceive checks if the update can be dispatched according to the given criteria
 func (s *Subscriber) CanReceive(u *Update) bool {
-	return s.isAuthorized(u) && s.isSubscribed(u)
+	return s.IsAuthorized(u) && s.IsSubscribed(u)
 }
 
-// isAuthorized checks if the subscriber can access to at least one of the update's intended targets
-func (s *Subscriber) isAuthorized(u *Update) bool {
+// IsAuthorized checks if the subscriber can access to at least one of the update's intended targets
+// Don't forget to also call IsSubscribed
+func (s *Subscriber) IsAuthorized(u *Update) bool {
 	if s.AllTargets || len(u.Targets) == 0 {
 		return true
 	}
@@ -46,8 +48,9 @@ func (s *Subscriber) isAuthorized(u *Update) bool {
 	return false
 }
 
-// isSubscribedToUpdate checks if the subscriber has subscribed to this update
-func (s *Subscriber) isSubscribed(u *Update) bool {
+// IsSubscribed checks if the subscriber has subscribed to this update
+// Don't forget to also call IsAuthorized
+func (s *Subscriber) IsSubscribed(u *Update) bool {
 	for _, ut := range u.Topics {
 		if match, ok := s.matchCache[ut]; ok {
 			return match
diff --git a/main.go b/main.go
index 003ea29f..b914095e 100644
--- a/main.go
+++ b/main.go
@@ -20,6 +20,10 @@ func init() {
 	case "FLUENTD":
 		log.SetFormatter(fluentd.NewFormatter())
 	}
+
+	if os.Getenv("DEBUG") == "1" {
+		log.SetLevel(log.DebugLevel)
+	}
 }
 
 func main() {