diff --git a/libraries/SITL/SITL.cpp b/libraries/SITL/SITL.cpp
index 9dc49f4af2..eddc79356e 100644
--- a/libraries/SITL/SITL.cpp
+++ b/libraries/SITL/SITL.cpp
@@ -81,6 +81,7 @@ const AP_Param::GroupInfo SITL::var_info[] = {
     AP_GROUPINFO("ADSB_ALT",      47, SITL,  adsb_altitude_m, 1000),
     AP_GROUPINFO("MAG_ALY",       48, SITL,  mag_anomaly_ned, 0),
     AP_GROUPINFO("MAG_ALY_HGT",   49, SITL,  mag_anomaly_hgt, 1.0f),
+    AP_GROUPINFO("PIN_MASK",      50, SITL,  pin_mask, 0),
     AP_GROUPEND
 };
 
diff --git a/libraries/SITL/SITL.h b/libraries/SITL/SITL.h
index 269ef55c0d..ded2d0e7cd 100644
--- a/libraries/SITL/SITL.h
+++ b/libraries/SITL/SITL.h
@@ -103,6 +103,7 @@ public:
     AP_Int16 flow_rate; // optflow data rate (Hz)
     AP_Int8  flow_delay; // optflow data delay
     AP_Int8  terrain_enable; // enable using terrain for height
+    AP_Int8  pin_mask; // for GPIO emulation
 
     // wind control
     float wind_speed_active;