diff --git a/src/mqttclient.cpp b/src/mqttclient.cpp
index a4d2564..42eafb8 100644
--- a/src/mqttclient.cpp
+++ b/src/mqttclient.cpp
@@ -215,9 +215,17 @@ void MqttClient::disconnect()
 
 Token MqttClient::publish(const MqttMessage& message, int qos)
 {
-    if (hasWildcard(message.topic()) || !isValidTopic(message.topic())) {
+    if (hasWildcard(message.topic()))
+    {
+        LogDebug("[MqttClient::publish]","Topic has wildcard : " + message.topic());
         return Token(m_clientId, -1);
     }
+    else if(!isValidTopic(message.topic()))
+    {
+        LogDebug("[MqttClient::publish]","Topic is invalid : " + message.topic());
+        return Token(m_clientId, -1);
+    }
+
     OSDEV_COMPONENTS_LOCKGUARD(m_interfaceMutex);
     IMqttClientImpl* client(nullptr);
     {
@@ -239,6 +247,13 @@ Token MqttClient::publish(const MqttMessage& message, int qos)
         }
         client = m_principalClient.get();
     }
+
+    if(!client)
+    {
+        LogDebug("[MqttClient::publish]", "Invalid pointer to IMqttClient retrieved.");
+        return Token(m_clientId, -1);
+    }
+
     return Token(client->clientId(), client->publish(message, qos));
 }
 
diff --git a/src/mqttutil.cpp b/src/mqttutil.cpp
index 4f22c15..a7b3376 100644
--- a/src/mqttutil.cpp
+++ b/src/mqttutil.cpp
@@ -55,7 +55,12 @@ bool isValidTopic( const std::string &topic )
 
 bool hasWildcard( const std::string &topic )
 {
-    return ( topic.size() > 0 && (topic.find( '+' ) != std::string::npos || topic.size() - 1 == '#' ) );
+    return ( topic.size() > 0 &&
+            (
+                topic.find( '+' ) != std::string::npos ||
+                topic.back() == '#'
+            )
+           );
 }
 
 bool testForOverlap( const std::string &existingTopic, const std::string &newTopic )