diff --git a/nature/init.lua b/nature/init.lua
index df31d8d..2b8b8c4 100644
--- a/nature/init.lua
+++ b/nature/init.lua
@@ -28,7 +28,9 @@ do
 				return got_virt
 			end
 
-			virt_G[key] = os.getenv(key)
+			if type(key) == 'string' then
+				virt_G[key] = os.getenv(key)
+			end
 			return virt_G[key]
 		end,