diff --git a/src/map_extras.cpp b/src/map_extras.cpp
index 09b7489d3c81e..5544b9f4867f6 100644
--- a/src/map_extras.cpp
+++ b/src/map_extras.cpp
@@ -373,18 +373,16 @@ static bool mx_helicopter( map &m, const tripoint_abs_sm &abs_sub )
         // we can rotate it and calculate its bounding box, but don't place it on the map.
         vehicle veh( crashed_hull );
         veh.turn( dir1 );
-        // Get the bounding box, centered on mount(0,0), move the wreckage forward/backward
-        // half it's length so that it spawns more over the center of the debris area
+        // Find where the center of the vehicle is and adjust the spawn position to get it centered in the
+        // debris area.
         const bounding_box bbox = veh.get_bounding_box();
-        const point_rel_ms length( std::abs( bbox.p2.x() - bbox.p1.x() ),
-                                   std::abs( bbox.p2.y() - bbox.p1.y() ) );
-        const point_rel_ms offset( veh.dir_vec().x * length.x() / 2, veh.dir_vec().y * length.y() / 2 );
-        const point_rel_ms min( std::abs( bbox.p1.x() ), std::abs( bbox.p1.y() ) );
-        const int x_max = SEEX * 2 - bbox.p2.x() - 1;
-        const int y_max = SEEY * 2 - bbox.p2.y() - 1;
 
+        point_rel_ms center_offset = {( bbox.p1.x() + bbox.p2.x() ) / 2, ( bbox.p1.y() + bbox.p2.y() ) / 2};
         // Clamp x1 & y1 such that no parts of the vehicle extend over the border of the submap.
-        wreckage_pos = { clamp( c.x() + offset.x(), min.x(), x_max ), clamp( c.y() + offset.y(), min.y(), y_max ), abs_sub.z()};
+
+        wreckage_pos = { clamp( c.x() - center_offset.x(), abs( bbox.p1.x() ), SEEX * 2 - 1 - abs( bbox.p2.x() ) ),
+                         clamp( c.y() - center_offset.y(), abs( bbox.p1.y() ), SEEY * 2 - 1 - abs( bbox.p2.y() ) ), abs_sub.z()
+                       };
     }
 
     vehicle *wreckage = m.add_vehicle( crashed_hull, wreckage_pos, dir1, rng( 1, 33 ), 1 );
diff --git a/src/vehicle.cpp b/src/vehicle.cpp
index 5d0b967376edb..024bc6aba8a59 100644
--- a/src/vehicle.cpp
+++ b/src/vehicle.cpp
@@ -1902,15 +1902,15 @@ bool vehicle::merge_appliance_into_grid( vehicle &veh_target )
 
     bounding_box vehicle_box = get_bounding_box( false, true );
     bounding_box target_vehicle_box = veh_target.get_bounding_box( false, true );
-
-    bounding_box combined_box;
-    combined_box.p1 = point_rel_ms( std::min( vehicle_box.p1.x(), target_vehicle_box.p1.x() ),
-                                    std::min( vehicle_box.p1.y(), target_vehicle_box.p1.y() ) );
-    combined_box.p2 = point_rel_ms( std::max( vehicle_box.p2.x(), target_vehicle_box.p2.x() ),
-                                    std::max( vehicle_box.p2.y(), target_vehicle_box.p2.y() ) );
+    const point_bub_ms min = { std::min( pos_bub().x() + vehicle_box.p1.x(), veh_target.pos_bub().x() + target_vehicle_box.p1.x() ),
+                               std::min( pos_bub().y() + vehicle_box.p1.y(), veh_target.pos_bub().y() + target_vehicle_box.p1.y() )
+                             };
+    const point_bub_ms max = { std::max( pos_bub().x() + vehicle_box.p1.x(), veh_target.pos_bub().x() + target_vehicle_box.p1.x() ),
+                               std::max( pos_bub().y() + vehicle_box.p1.y(), veh_target.pos_bub().y() + target_vehicle_box.p1.y() )
+                             };
     point_rel_ms size;
-    size.x() = std::abs( ( combined_box.p2 - combined_box.p1 ).x() ) + 1;
-    size.y() = std::abs( ( combined_box.p2 - combined_box.p1 ).y() ) + 1;
+    size.x() = std::abs( ( max - min ).x() ) + 1;
+    size.y() = std::abs( ( max - min ).y() ) + 1;
 
     //Make sure the resulting vehicle would not be too large
     if( size.x() <= MAX_WIRE_VEHICLE_SIZE && size.y() <= MAX_WIRE_VEHICLE_SIZE ) {
@@ -8256,17 +8256,13 @@ bounding_box vehicle::get_bounding_box( bool use_precalc, bool no_fake )
         point_rel_ms pt;
         if( use_precalc ) {
             const int i_use = 0;
-            // TODO: Check if this is correct. part_at takes a vehicle relative position, not a bub one...
-            // int part_idx = part_at((p - pos_abs()).xy()); // Suggested correction.
-            int part_idx = part_at( rebase_rel( get_map().get_bub( p ).xy() ) );
+            int part_idx = part_at( ( p - pos_abs() ).xy() );
             if( part_idx < 0 ) {
                 continue;
             }
             pt = parts[part_idx].precalc[i_use].xy();
         } else {
-            // TODO: Check if this is correct. part_at takes a vehicle relative position, not a bub one...
-            // pt = (p - pos_abs()).xy(); // Suggested correction.
-            pt = rebase_rel( get_map().get_bub( p ).xy() );
+            pt = ( p - pos_abs() ).xy();
         }
         if( pt.x() < min_x ) {
             min_x = pt.x();