diff --git a/mods/mobs/api.lua b/mods/mobs/api.lua
index 75a6fea9..de0bc049 100755
--- a/mods/mobs/api.lua
+++ b/mods/mobs/api.lua
@@ -212,11 +212,13 @@ function mobs:register_mob(name, def)
 			and self.child == false
 			and math.random(1,self.replace_rate) == 1 then
 				local pos = self.object:getpos()
+				local nodeunder = minetest.get_node_or_nil({x=pos.x, y=pos.y-1, z=pos.z})
 				pos.y = pos.y + self.replace_offset
 				-- print ("replace node = ".. minetest.get_node(pos).name, pos.y)
 				if self.replace_what
 				and self.object:getvelocity().y == 0
-				and #minetest.find_nodes_in_area(pos, pos, self.replace_what) > 0 then
+				and #minetest.find_nodes_in_area(pos, pos, self.replace_what) > 0 --then
+				and nodeunder and nodeunder.name ~= "air" then
 				--and self.state == "stand" then
 					minetest.set_node(pos, {name = self.replace_with})
 				end