diff --git a/src/TypeDef.h b/src/TypeDef.h
index d278fa8d..a0163d2b 100644
--- a/src/TypeDef.h
+++ b/src/TypeDef.h
@@ -57,53 +57,55 @@
 #define UART_FLOW_BOTH                        0x03
 
 // Common status codes
-#define ERR_NONE                              0x00
-#define ERR_UNKNOWN                           0x63  // maximum status code value is 99 DEC, so that it does not interfere with HTTP status codes
+#define ERR_NONE                               0
+#define ERR_UNKNOWN                            -1
 
 // SX1278/SX1272/RF69 status codes
-#define ERR_CHIP_NOT_FOUND                    0x01
-#define ERR_EEPROM_NOT_INITIALIZED            0x02
-#define ERR_PACKET_TOO_LONG                   0x03
-#define ERR_TX_TIMEOUT                        0x04
-#define ERR_RX_TIMEOUT                        0x05
-#define ERR_CRC_MISMATCH                      0x06
-#define ERR_INVALID_BANDWIDTH                 0x07
-#define ERR_INVALID_SPREADING_FACTOR          0x08
-#define ERR_INVALID_CODING_RATE               0x09
-#define ERR_INVALID_BIT_RANGE                 0x0A
-#define ERR_INVALID_FREQUENCY                 0x0B
-#define ERR_INVALID_OUTPUT_POWER              0x0C
-#define PREAMBLE_DETECTED                     0x0D
-#define CHANNEL_FREE                          0x0E
+#define ERR_CHIP_NOT_FOUND                    -2
+#define ERR_EEPROM_NOT_INITIALIZED            -3
+#define ERR_PACKET_TOO_LONG                   -4
+#define ERR_TX_TIMEOUT                        -5
+#define ERR_RX_TIMEOUT                        -6
+#define ERR_CRC_MISMATCH                      -7
+#define ERR_INVALID_BANDWIDTH                 -8
+#define ERR_INVALID_SPREADING_FACTOR          -9
+#define ERR_INVALID_CODING_RATE               -10
+#define ERR_INVALID_BIT_RANGE                 -11
+#define ERR_INVALID_FREQUENCY                 -12
+#define ERR_INVALID_OUTPUT_POWER              -13
+#define PREAMBLE_DETECTED                     -14
+#define CHANNEL_FREE                          -15
+#define ERR_SPI_WRITE_FAILED                  -16
 
 // RF69-specific status codes
-#define ERR_INVALID_BIT_RATE                  0x0F
-#define ERR_INVALID_FREQUENCY_DEVIATION       0x10
-#define ERR_INVALID_BIT_RATE_BW_RATIO         0x11
-#define ERR_INVALID_RX_BANDWIDTH              0x12
-#define ERR_INVALID_SYNC_WORD                 0x13
+#define ERR_INVALID_BIT_RATE                  -101
+#define ERR_INVALID_FREQUENCY_DEVIATION       -102
+#define ERR_INVALID_BIT_RATE_BW_RATIO         -103
+#define ERR_INVALID_RX_BANDWIDTH              -104
+#define ERR_INVALID_SYNC_WORD                 -105
 
 // ESP8266 status codes
-#define ERR_AT_FAILED                         0x01
-#define ERR_URL_MALFORMED                     0x02
-#define ERR_RESPONSE_MALFORMED_AT             0x03
-#define ERR_RESPONSE_MALFORMED                0x04
-#define ERR_MQTT_CONN_VERSION_REJECTED        0x05
-#define ERR_MQTT_CONN_ID_REJECTED             0x06
-#define ERR_MQTT_CONN_SERVER_UNAVAILABLE      0x07
-#define ERR_MQTT_CONN_BAD_USERNAME_PASSWORD   0x08
-#define ERR_MQTT_CONN_NOT_AUTHORIZED          0x09
-#define ERR_MQTT_UNEXPECTED_PACKET_ID         0x0A
-#define ERR_MQTT_NO_NEW_PACKET_AVAILABLE      0x0B
+#define ERR_AT_FAILED                         -201
+#define ERR_URL_MALFORMED                     -202
+#define ERR_RESPONSE_MALFORMED_AT             -203
+#define ERR_RESPONSE_MALFORMED                -204
+#define ERR_MQTT_CONN_VERSION_REJECTED        -205
+#define ERR_MQTT_CONN_ID_REJECTED             -206
+#define ERR_MQTT_CONN_SERVER_UNAVAILABLE      -207
+#define ERR_MQTT_CONN_BAD_USERNAME_PASSWORD   -208
+#define ERR_MQTT_CONN_NOT_AUTHORIZED          -208
+#define ERR_MQTT_UNEXPECTED_PACKET_ID         -209
+#define ERR_MQTT_NO_NEW_PACKET_AVAILABLE      -210
 #define MQTT_SUBS_SUCCESS_QOS_0               0x00
 #define MQTT_SUBS_SUCCESS_QOS_1               0x01
 #define MQTT_SUBS_SUCCESS_QOS_2               0x02
 #define ERR_MQTT_SUBS_FAILED                  0x80
 
 // XBee status codes
-#define ERR_CMD_MODE_FAILED                   0x02
-#define ERR_FRAME_MALFORMED                   0x03
-#define ERR_FRAME_INCORRECT_CHECKSUM          0x04
-#define ERR_FRAME_UNEXPECTED_ID               0x05
+#define ERR_AT_FAILED                         -301
+#define ERR_CMD_MODE_FAILED                   -302
+#define ERR_FRAME_MALFORMED                   -303
+#define ERR_FRAME_INCORRECT_CHECKSUM          -304
+#define ERR_FRAME_UNEXPECTED_ID               -305
 
 #endif