diff --git a/include/lwmqtt.h b/include/lwmqtt.h
index 0e727d1..e2c3274 100644
--- a/include/lwmqtt.h
+++ b/include/lwmqtt.h
@@ -223,12 +223,13 @@ typedef struct {
  * The available return codes transported by the connack packet.
  */
 typedef enum {
-  LWMQTT_CONNACK_CONNECTION_ACCEPTED = 0,
-  LWMQTT_CONNACK_UNACCEPTABLE_PROTOCOL = 1,
-  LWMQTT_CONNACK_IDENTIFIER_REJECTED = 2,
-  LWMQTT_CONNACK_SERVER_UNAVAILABLE = 3,
-  LWMQTT_CONNACK_BAD_USERNAME_OR_PASSWORD = 4,
-  LWMQTT_CONNACK_NOT_AUTHORIZED = 5
+  LWMQTT_CONNECTION_ACCEPTED = 0,
+  LWMQTT_UNACCEPTABLE_PROTOCOL = 1,
+  LWMQTT_IDENTIFIER_REJECTED = 2,
+  LWMQTT_SERVER_UNAVAILABLE = 3,
+  LWMQTT_BAD_USERNAME_OR_PASSWORD = 4,
+  LWMQTT_NOT_AUTHORIZED = 5,
+  LWMQTT_UNKNOWN_RETURN_CODE = 6
 } lwmqtt_return_code_t;
 
 /**
diff --git a/src/client.c b/src/client.c
index 5c83fc5..3342e4f 100644
--- a/src/client.c
+++ b/src/client.c
@@ -400,7 +400,7 @@ lwmqtt_err_t lwmqtt_connect(lwmqtt_client_t *client, lwmqtt_options_t options, l
   }
 
   // return error if connection was not accepted
-  if (*return_code != LWMQTT_CONNACK_CONNECTION_ACCEPTED) {
+  if (*return_code != LWMQTT_CONNECTION_ACCEPTED) {
     return LWMQTT_CONNECTION_DENIED;
   }
 
diff --git a/src/packet.c b/src/packet.c
index 0d1ac48..2a35c32 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -271,9 +271,32 @@ lwmqtt_err_t lwmqtt_decode_connack(uint8_t *buf, size_t buf_len, bool *session_p
     return err;
   }
 
-  // set variables
+  // set session present
   *session_present = flags.bits.session_present == 1;
-  *return_code = (lwmqtt_return_code_t)raw_return_code;
+
+  // set return code
+  switch (raw_return_code) {
+    case 0:
+      *return_code = LWMQTT_CONNECTION_ACCEPTED;
+      break;
+    case 1:
+      *return_code = LWMQTT_UNACCEPTABLE_PROTOCOL;
+      break;
+    case 2:
+      *return_code = LWMQTT_IDENTIFIER_REJECTED;
+      break;
+    case 3:
+      *return_code = LWMQTT_SERVER_UNAVAILABLE;
+      break;
+    case 4:
+      *return_code = LWMQTT_BAD_USERNAME_OR_PASSWORD;
+      break;
+    case 5:
+      *return_code = LWMQTT_NOT_AUTHORIZED;
+      break;
+    default:
+      *return_code = LWMQTT_UNKNOWN_RETURN_CODE;
+  }
 
   return LWMQTT_SUCCESS;
 }
diff --git a/tests/packet.cpp b/tests/packet.cpp
index 27b2de8..fef8ab6 100644
--- a/tests/packet.cpp
+++ b/tests/packet.cpp
@@ -197,8 +197,8 @@ TEST(ConnackTest, Decode1) {
   lwmqtt_err_t err = lwmqtt_decode_connack(pkt, 4, &session_present, &return_code);
 
   EXPECT_EQ(err, LWMQTT_SUCCESS);
-  EXPECT_EQ(session_present, 0);
-  EXPECT_EQ(return_code, 0);
+  EXPECT_EQ(session_present, false);
+  EXPECT_EQ(return_code, LWMQTT_CONNECTION_ACCEPTED);
 }
 
 TEST(ConnackTest, DecodeError1) {