diff --git a/libraries/AP_Logger/LogStructure.h b/libraries/AP_Logger/LogStructure.h
index c6972e1a01..d3ecd18388 100644
--- a/libraries/AP_Logger/LogStructure.h
+++ b/libraries/AP_Logger/LogStructure.h
@@ -1232,7 +1232,7 @@ struct PACKED log_Arm_Disarm {
 
 #define ACC_LABELS "TimeUS,SampleUS,AccX,AccY,AccZ"
 #define ACC_FMT   "QQfff"
-#define ACC_UNITS "ssnnn"
+#define ACC_UNITS "ssooo"
 #define ACC_MULTS "FF000"
 
 // see "struct sensor" in AP_Baro.h and "Write_Baro":