diff --git a/sw/airborne/modules/gps/gps_ubx_ucenter.c b/sw/airborne/modules/gps/gps_ubx_ucenter.c
index d86c636e67..7aa7d3654b 100644
--- a/sw/airborne/modules/gps/gps_ubx_ucenter.c
+++ b/sw/airborne/modules/gps/gps_ubx_ucenter.c
@@ -19,10 +19,21 @@
  * Boston, MA 02111-1307, USA.
  */
 
-#define GPS_UBX_UCENTER_RUNNING    1
-#define GPX_UBX_UCENTER_STOPPED    0
+#include "gps_ubx_ucenter.h"
+
+#define GPS_UBX_UCENTER_STATUS_RUNNING    1
+#define GPS_UBX_UCENTER_STATUS_STOPPED    0
+
+#define GPS_UBX_UCENTER_REPLY_NONE        0
+#define GPS_UBX_UCENTER_REPLY_ACK         1
+#define GPS_UBX_UCENTER_REPLY_NACK        2
+
+/** Space Vehicle Information */
+struct gps_ubx_ucenter_t {
+  uint8_t status;
+  uint8_t reply;
+} gps_ubx_ucenter;
 
-uint8_t gps_ubx_ucenter_status
 
 /////////////////////////////
 // Periodic Function
@@ -30,7 +41,8 @@ uint8_t gps_ubx_ucenter_status
 void gps_ubx_ucenter_init(void)
 {
   // Start UCenter
-  gps_ubx_ucenter_status = GPS_UBX_UCENTER_RUNNING;
+  gps_ubx_ucenter.status = GPS_UBX_UCENTER_STATUS_RUNNING;
+  gps_ubx_ucenter.reply = GPS_UBX_UCENTER_REPLY_NONE;
 }
 
 
@@ -41,7 +53,7 @@ void gps_ubx_ucenter_init(void)
 void gps_ubx_ucenter_periodic(void)
 {
   // Save processing time inflight
-  if (gps_ubx_ucenter_status == GPX_UBX_UCENTER_STOPPED)
+  if (gps_ubx_ucenter.status == GPS_UBX_UCENTER_STATUS_STOPPED)
     return;
 
   // Autobaud
@@ -55,18 +67,21 @@ void gps_ubx_ucenter_periodic(void)
 void gps_ubx_ucenter_event(void)
 {
   // Save processing time inflight
-  if (gps_ubx_ucenter_status == GPX_UBX_UCENTER_STOPPED)
+  if (gps_ubx_ucenter_status == GPS_UBX_UCENTER_STATUS_STOPPED)
     return;
 
-  // Which Message
-  if (gps_ubx.msg_class == UBX_NAV_ID) {
-    if (gps_ubx.msg_id == UBX_NAV_SOL_ID) {
-    }
-  }    
+  // Read Configuration Reply's
   if (gps_ubx.msg_class == UBX_ACK_ID) {
     if (gps_ubx.msg_id == UBX_ACK_ACK_ID) {
-      gps_status_config++;
+      gps_ubx_ucenter.reply = GPX_UBX_UCENTER_REPLY_ACK;
     }
+    else
+    {
+      gps_ubx_ucenter.reply = GPX_UBX_UCENTER_REPLY_NACK;
+    }
+  }
+  // Version info
+  else if (gps_ubx.msg_class == UBX_ACK_ID) {
   }
 }
 
@@ -209,7 +224,6 @@ void gps_configure( void ) {
   }
   gps_configuring = user_gps_configure(gps_status_config);
 }
-#endif /* GPS_CONFIGURE */
 #endif // GPS_CONFIGURE
 
  */
diff --git a/sw/airborne/modules/gps/gps_ubx_ucenter.h b/sw/airborne/modules/gps/gps_ubx_ucenter.h
index f2b9d3c9da..1453b18279 100644
--- a/sw/airborne/modules/gps/gps_ubx_ucenter.h
+++ b/sw/airborne/modules/gps/gps_ubx_ucenter.h
@@ -27,6 +27,7 @@
 #ifndef GPS_UBX_UCENTER_H
 #define GPS_UBX_UCENTER_H
 
+extern void gps_ubx_ucenter_init(void);
 extern void gps_ubx_ucenter_periodic(void);
 extern void gps_ubx_ucenter_event(void);
 
diff --git a/sw/airborne/subsystems/gps/gps_ubx.c b/sw/airborne/subsystems/gps/gps_ubx.c
index dc66f807fb..2add2569bc 100644
--- a/sw/airborne/subsystems/gps/gps_ubx.c
+++ b/sw/airborne/subsystems/gps/gps_ubx.c
@@ -388,7 +388,7 @@ void gps_configure( void ) {
 #endif /* GPS_CONFIGURE */
 
 #ifdef GPS_UBX_UCENTER
-#include GPX_UBX_UCENTER
+#include GPS_UBX_UCENTER
 #endif
 
 
diff --git a/sw/airborne/subsystems/gps/gps_ubx.h b/sw/airborne/subsystems/gps/gps_ubx.h
index a3ed13cd5a..e31f43272c 100644
--- a/sw/airborne/subsystems/gps/gps_ubx.h
+++ b/sw/airborne/subsystems/gps/gps_ubx.h
@@ -78,10 +78,7 @@ extern bool_t gps_configuring;
 #define GpsParseOrConfigure() gps_ubx_read_message()
 #endif
 
-#ifdef GPS_UBX_UCENTER
-extern void gps_ubx_ucenter_periodic(void);
-extern void gps_ubx_ucenter_event(void);
-#else
+#ifndef GPS_UBX_UCENTER
 #define gps_ubx_ucenter_event() {}
 #endif