diff --git a/changelog.txt b/changelog.txt
index 389db79aa7..5525bfd3d7 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -44,6 +44,7 @@ Template for new versions:
 - `ban-cooking`: fix banning creature alcohols resulting in error
 - `confirm`: properly detect clicks on the remove zone button even when the unit selection screen is also open (e.g. the vanilla assign animal to pasture panel)
 - `quickfort`: if a blueprint specifies an up/down stair, but the tile the blueprint is applied to cannot make an up stair (e.g. it has already been dug out), still designate a down stair if possible
+- `suspendmanager`: correctly handle building collisions with smoothing designations when the building is on the edge of the map
 
 ## Misc Improvements
 - `gui/control-panel`: reduce frequency for `warn-stranded` check to once every 2 days
diff --git a/suspendmanager.lua b/suspendmanager.lua
index 9c010e2d3e..591f09ef0c 100644
--- a/suspendmanager.lua
+++ b/suspendmanager.lua
@@ -595,7 +595,8 @@ local function buildingOnDesignation(building)
     for x=building.x1,building.x2 do
         for y=building.y1,building.y2 do
             local flags, occupancy = dfhack.maps.getTileFlags(x,y,z)
-            if flags.dig ~= df.tile_dig_designation.No or
+            if not flags then goto continue end
+            if flags and flags.dig ~= df.tile_dig_designation.No or
                 flags.smooth > 0 or
                 occupancy.carve_track_north or
                 occupancy.carve_track_east or
@@ -604,6 +605,7 @@ local function buildingOnDesignation(building)
             then
                 return true
             end
+            ::continue::
         end
     end
 end