diff --git a/5/21/truck-soft/car.lua b/5/21/truck-soft/car.lua
index 27d77fc..3fdc523 100644
--- a/5/21/truck-soft/car.lua
+++ b/5/21/truck-soft/car.lua
@@ -350,7 +350,7 @@ function process_node(profile, node, result, relations)
       local restricted_by_height = false
       if barrier == 'height_restrictor' then
          local maxheight = Measure.get_max_height(node:get_value_by_key("maxheight"), node)
-         restricted_by_height = maxheight and maxheight < profile.vehicle_height
+         restricted_by_height = maxheight and tonumber(maxheight) and tonumber(maxheight) < profile.vehicle_height
       end
 
       --  make an exception for rising bollard barriers
diff --git a/5/21/truck-soft/lib/way_handlers.lua b/5/21/truck-soft/lib/way_handlers.lua
index 356cf57..cc39f22 100644
--- a/5/21/truck-soft/lib/way_handlers.lua
+++ b/5/21/truck-soft/lib/way_handlers.lua
@@ -480,11 +480,11 @@ function WayHandlers.handle_height(profile,way,result,data)
   forward = Measure.get_max_height(forward,way)
   backward = Measure.get_max_height(backward,way)
 
-  if forward and forward < profile.vehicle_height then
+  if forward and tonumber(forward) and tonumber(forward) < profile.vehicle_height then
     result.forward_mode = mode.inaccessible
   end
 
-  if backward and backward < profile.vehicle_height then
+  if backward and tonumber(backward) and tonumber(backward) < profile.vehicle_height then
     result.backward_mode = mode.inaccessible
   end
 end