diff --git a/libraries/AP_GPS/AP_GPS_MTK.h b/libraries/AP_GPS/AP_GPS_MTK.h
index b5b1981730..fb9dd88619 100644
--- a/libraries/AP_GPS/AP_GPS_MTK.h
+++ b/libraries/AP_GPS/AP_GPS_MTK.h
@@ -16,6 +16,7 @@
 #define __AP_GPS_MTK_H__
 
 #include "GPS.h"
+#include <AP_Common.h>
 #include "AP_GPS_MTK_Common.h"
 
 class AP_GPS_MTK : public GPS {
@@ -31,8 +32,7 @@ public:
     static bool _detect(uint8_t );
 
 private:
-    #pragma pack(push,1)
-    struct diyd_mtk_msg {
+    struct PACKED diyd_mtk_msg {
         int32_t latitude;
         int32_t longitude;
         int32_t altitude;
@@ -42,7 +42,6 @@ private:
         uint8_t fix_type;
         uint32_t utc_time;
     };
-    #pragma pack(pop)
     enum diyd_mtk_fix_type {
         FIX_NONE = 1,
         FIX_2D = 2,
@@ -65,7 +64,7 @@ private:
     uint8_t         _payload_counter;
 
     // Receive buffer
-    union {
+    union PACKED {
         diyd_mtk_msg msg;
         uint8_t bytes[];
     } _buffer;
diff --git a/libraries/AP_GPS/AP_GPS_MTK19.h b/libraries/AP_GPS/AP_GPS_MTK19.h
index 0e38e08653..999f853144 100644
--- a/libraries/AP_GPS/AP_GPS_MTK19.h
+++ b/libraries/AP_GPS/AP_GPS_MTK19.h
@@ -14,6 +14,7 @@
 #define AP_GPS_MTK19_h
 
 #include "GPS.h"
+#include <AP_Common.h>
 #include "AP_GPS_MTK_Common.h"
 
 #define MTK_GPS_REVISION_V16  16
@@ -34,8 +35,7 @@ public:
     static bool 		_detect(uint8_t );
 
 private:
-	#pragma pack(push,1)
-    struct diyd_mtk_msg {
+    struct PACKED diyd_mtk_msg {
         int32_t latitude;
         int32_t longitude;
         int32_t altitude;
@@ -47,7 +47,6 @@ private:
         uint32_t utc_time;
         uint16_t hdop;
     };
-	#pragma pack(pop)
     enum diyd_mtk_fix_type {
         FIX_NONE = 1,
         FIX_2D = 2,
diff --git a/libraries/AP_GPS/AP_GPS_SIRF.h b/libraries/AP_GPS/AP_GPS_SIRF.h
index e6df84c9f6..61b35f9075 100644
--- a/libraries/AP_GPS/AP_GPS_SIRF.h
+++ b/libraries/AP_GPS/AP_GPS_SIRF.h
@@ -12,6 +12,7 @@
 #define __AP_GPS_SIRF_H__
 
 #include <AP_HAL.h>
+#include <AP_Common.h>
 #include "GPS.h"
 
 #define SIRF_SET_BINARY "$PSRF100,0,38400,8,1,0*3C"
@@ -32,8 +33,7 @@ public:
 	static bool         _detect(uint8_t data);
 
 private:
-    #pragma pack(push,1)
-    struct sirf_geonav {
+    struct PACKED sirf_geonav {
         uint16_t fix_invalid;
         uint16_t fix_type;
         uint16_t week;
@@ -70,7 +70,6 @@ private:
         uint8_t hdop;
         uint8_t mode_info;
     };
-    #pragma pack(pop)
     enum sirf_protocol_bytes {
         PREAMBLE1 = 0xa0,
         PREAMBLE2 = 0xa2,
diff --git a/libraries/AP_GPS/AP_GPS_UBLOX.h b/libraries/AP_GPS/AP_GPS_UBLOX.h
index c8422abf71..e77394bc0c 100644
--- a/libraries/AP_GPS/AP_GPS_UBLOX.h
+++ b/libraries/AP_GPS/AP_GPS_UBLOX.h
@@ -13,6 +13,7 @@
 #define __AP_GPS_UBLOX_H__
 
 #include <AP_HAL.h>
+#include <AP_Common.h>
 #include "GPS.h"
 
 /*
@@ -55,25 +56,24 @@ public:
 
 private:
     // u-blox UBX protocol essentials
-	#pragma pack(push,1)
-    struct ubx_header {
+    struct PACKED ubx_header {
         uint8_t preamble1;
         uint8_t preamble2;
         uint8_t msg_class;
         uint8_t msg_id;
         uint16_t length;
     };
-    struct ubx_cfg_nav_rate {
+    struct PACKED ubx_cfg_nav_rate {
         uint16_t measure_rate_ms;
         uint16_t nav_rate;
         uint16_t timeref;
     };
-    struct ubx_cfg_msg_rate {
+    struct PACKED ubx_cfg_msg_rate {
         uint8_t msg_class;
         uint8_t msg_id;
         uint8_t rate;
     };
-    struct ubx_cfg_nav_settings {
+    struct PACKED ubx_cfg_nav_settings {
         uint16_t mask;
         uint8_t dynModel;
         uint8_t fixMode;
@@ -92,7 +92,7 @@ private:
         uint32_t res4;
     };
 
-    struct ubx_nav_posllh {
+    struct PACKED ubx_nav_posllh {
         uint32_t time;                                  // GPS msToW
         int32_t longitude;
         int32_t latitude;
@@ -101,7 +101,7 @@ private:
         uint32_t horizontal_accuracy;
         uint32_t vertical_accuracy;
     };
-    struct ubx_nav_status {
+    struct PACKED ubx_nav_status {
         uint32_t time;                                  // GPS msToW
         uint8_t fix_type;
         uint8_t fix_status;
@@ -110,7 +110,7 @@ private:
         uint32_t time_to_first_fix;
         uint32_t uptime;                                // milliseconds
     };
-    struct ubx_nav_solution {
+    struct PACKED ubx_nav_solution {
         uint32_t time;
         int32_t time_nsec;
         int16_t week;
@@ -129,7 +129,7 @@ private:
         uint8_t satellites;
         uint32_t res2;
     };
-    struct ubx_nav_velned {
+    struct PACKED ubx_nav_velned {
         uint32_t time;                                  // GPS msToW
         int32_t ned_north;
         int32_t ned_east;
@@ -141,7 +141,7 @@ private:
         uint32_t heading_accuracy;
     };
     // Receive buffer
-    union {
+    union PACKED {
         ubx_nav_posllh posllh;
         ubx_nav_status status;
         ubx_nav_solution solution;
@@ -149,7 +149,6 @@ private:
         ubx_cfg_nav_settings nav_settings;
         uint8_t bytes[];
     } _buffer;
-	#pragma pack(pop)
 
     enum ubs_protocol_bytes {
         PREAMBLE1 = 0xb5,