diff --git a/fc.ino b/fc.ino
index fb0e1ef..7ebe4b2 100644
--- a/fc.ino
+++ b/fc.ino
@@ -34,26 +34,26 @@ int read_line = 22;
 int rx2 = 16;
 int tx2 = 17;
 
-typedef struct {
+typedef struct __attribute__((packed)) {
   uint8_t type;
   uint8_t controller_version;
   uint8_t unknown[12];
   uint16_t crc;
 } pkt_init_t;
 
-typedef struct {
+typedef struct __attribute__((packed)) {
   uint8_t type;
   uint8_t unknown[13];
   uint16_t crc;
 } pkt_init_resp_t;
 
-typedef struct {
+typedef struct __attribute__((packed)) {
   uint8_t type;
   uint8_t unknown[13];
   uint16_t crc;
 } pkt_init_2_t;
 
-typedef struct {
+typedef struct __attribute__((packed)) {
   uint8_t type;
   uint8_t ack_type;
   uint8_t unknown_1;
@@ -63,7 +63,7 @@ typedef struct {
   uint16_t crc;
 } pkt_ack_t;
 
-typedef struct {
+typedef struct __attribute__((packed)) {
   uint8_t type;
   uint8_t unknown[29];
   uint16_t crc;