diff --git a/mods/nodes/init.lua b/mods/nodes/init.lua
index f7cb2a5..19b7251 100644
--- a/mods/nodes/init.lua
+++ b/mods/nodes/init.lua
@@ -1440,7 +1440,13 @@ for _, names in ipairs({
 					itemstack:add_item(name)
 					return itemstack
 				end
-				clicker:get_inventory():add_item("main", name)
+				local inv = clicker:get_inventory()
+				-- prevent stacking of tools, but not nexus blocks.
+				if name == "boxes:nexus" then
+					inv:add_item("main", name)
+				elseif not inv:contains_item("main", name) then
+					inv:add_item("main", name)
+				end
 			end
 			return itemstack
 		end,