diff --git a/ROMFS/px4fmu_common/mixers-sitl/plane_sitl.main.mix b/ROMFS/px4fmu_common/mixers-sitl/plane_sitl.main.mix
index f69470276516..5fd6115f46b9 100644
--- a/ROMFS/px4fmu_common/mixers-sitl/plane_sitl.main.mix
+++ b/ROMFS/px4fmu_common/mixers-sitl/plane_sitl.main.mix
@@ -34,3 +34,8 @@ S: 0 0  10000  10000    0 -10000  10000
 M: 1
 O:       10000   10000   0 -10000  10000
 S: 0 1   10000   10000    0 -10000  10000
+
+# mixer for the flaps
+M: 1
+O:       10000   10000   0 -10000  10000
+S: 0 4   10000   10000    0 -10000  10000