diff --git a/libraries/AP_HAL_SITL/Util.cpp b/libraries/AP_HAL_SITL/Util.cpp
index fd03effb1d..4f8eec1950 100644
--- a/libraries/AP_HAL_SITL/Util.cpp
+++ b/libraries/AP_HAL_SITL/Util.cpp
@@ -72,7 +72,7 @@ bool HALSITL::Util::get_system_id_unformatted(uint8_t buf[], uint8_t &len)
   as get_system_id_unformatted will already be ascii, we use the same
   ID here
  */
-bool HALSITL::Util::get_system_id(char buf[40])
+bool HALSITL::Util::get_system_id(char buf[50])
 {
     uint8_t len = 40;
     return get_system_id_unformatted((uint8_t *)buf, len);
diff --git a/libraries/AP_HAL_SITL/Util.h b/libraries/AP_HAL_SITL/Util.h
index 816ff7876f..3c7576556d 100644
--- a/libraries/AP_HAL_SITL/Util.h
+++ b/libraries/AP_HAL_SITL/Util.h
@@ -42,7 +42,7 @@ public:
     void set_hw_rtc(uint64_t time_utc_usec) override { /* fail silently */ }
 
 
-    bool get_system_id(char buf[40]) override;
+    bool get_system_id(char buf[50]) override;
     bool get_system_id_unformatted(uint8_t buf[], uint8_t &len) override;
     void dump_stack_trace();