diff --git a/Tools/Replay/LogReader.cpp b/Tools/Replay/LogReader.cpp
index 083e262de4..9e28aa1666 100644
--- a/Tools/Replay/LogReader.cpp
+++ b/Tools/Replay/LogReader.cpp
@@ -150,7 +150,7 @@ void LogReader::process_plane(uint8_t type, uint8_t *data, uint16_t length)
     case LOG_PLANE_ATTITUDE_MSG: {
         struct log_Plane_Attitude msg;
         if(sizeof(msg) != length) {
-            printf("Bad ATTITUDE length\n");
+            printf("Bad ATTITUDE length %u should be %u\n", (unsigned)length, (unsigned)sizeof(msg));
             exit(1);
         }
         memcpy(&msg, data, sizeof(msg));
@@ -290,7 +290,9 @@ bool LogReader::update(uint8_t &type)
         if (::read(fd, &f.type, sizeof(f)-3) != sizeof(f)-3) {
             return false;
         }
-        num_formats++;
+        if (num_formats < LOGREADER_MAX_FORMATS-1) {
+            num_formats++;
+        }
         type = f.type;
         return true;
     }
diff --git a/Tools/Replay/LogReader.h b/Tools/Replay/LogReader.h
index 772dafaf66..afa04a6835 100644
--- a/Tools/Replay/LogReader.h
+++ b/Tools/Replay/LogReader.h
@@ -1,9 +1,9 @@
 
 enum log_messages {
     // plane specific messages
-    LOG_PLANE_ATTITUDE_MSG = 10,
-    LOG_PLANE_COMPASS_MSG  = 12,
-    LOG_PLANE_AIRSPEED_MSG  = 18,
+    LOG_PLANE_ATTITUDE_MSG = 9,
+    LOG_PLANE_COMPASS_MSG  = 11,
+    LOG_PLANE_AIRSPEED_MSG  = 17,
 
     // copter specific messages
     LOG_COPTER_ATTITUDE_MSG = 1,
@@ -51,8 +51,9 @@ private:
 
     uint32_t ground_alt_cm;
 
+#define LOGREADER_MAX_FORMATS 100
     uint8_t num_formats;
-    struct log_Format formats[100];
+    struct log_Format formats[LOGREADER_MAX_FORMATS];
 
     Vector3f attitude;
     Vector3f sim_attitude;