diff --git a/libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp b/libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp
index ac298850e6..5c308ea5db 100644
--- a/libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp
+++ b/libraries/GCS_MAVLink/MissionItemProtocol_Fence.cpp
@@ -230,7 +230,7 @@ MAV_MISSION_RESULT MissionItemProtocol_Fence::allocate_receive_resources(const u
 MAV_MISSION_RESULT MissionItemProtocol_Fence::allocate_update_resources()
 {
     const uint16_t _item_count = _fence.polyfence().num_stored_items();
-    _updated_mask = new uint8_t[(_item_count+7/8)];
+    _updated_mask = new uint8_t[(_item_count+7)/8];
     if (_updated_mask == nullptr) {
         return MAV_MISSION_ERROR;
     }