diff --git a/Adafruit_MQTT.cpp b/Adafruit_MQTT.cpp
index 8c461dd..ae7b062 100644
--- a/Adafruit_MQTT.cpp
+++ b/Adafruit_MQTT.cpp
@@ -84,6 +84,7 @@ Adafruit_MQTT::Adafruit_MQTT(const char *server, uint16_t port,
     subscriptions[i] = 0;
   }
 
+  packet_id_counter = 0;
 }
 
 Adafruit_MQTT::Adafruit_MQTT(const __FlashStringHelper *server,
@@ -103,6 +104,7 @@ Adafruit_MQTT::Adafruit_MQTT(const __FlashStringHelper *server,
     subscriptions[i] = 0;
   }
 
+  packet_id_counter = 0;
 }
 
 int8_t Adafruit_MQTT::connect() {
@@ -355,10 +357,13 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
   p+=2;
   // fill in packet[1] last
 
-  if(MQTT_PROTOCOL_LEVEL == 3)
+#if MQTT_PROTOCOL_LEVEL == 3
     p = stringprint_P(p, PSTR("MQIsdp"));
-  else
+#elif MQTT_PROTOCOL_LEVEL == 4
     p = stringprint_P(p, PSTR("MQTT"));
+#else
+    #error "MQTT level not supported"
+#endif
 
   p[0] = MQTT_PROTOCOL_LEVEL;
   p++;
diff --git a/Adafruit_MQTT.h b/Adafruit_MQTT.h
index 382dd87..eaed311 100644
--- a/Adafruit_MQTT.h
+++ b/Adafruit_MQTT.h
@@ -201,7 +201,7 @@ class Adafruit_MQTT {
   uint8_t will_qos;
   uint8_t will_retain;
   uint8_t buffer[MAXBUFFERSIZE];  // one buffer, used for all incoming/outgoing
-  uint16_t packet_id_counter = 0;
+  uint16_t packet_id_counter;
 
  private:
   Adafruit_MQTT_Subscribe *subscriptions[MAXSUBSCRIPTIONS];