diff --git a/functions/unearthing_biters.lua b/functions/unearthing_biters.lua
index 0be3a2fb..bcb53126 100644
--- a/functions/unearthing_biters.lua
+++ b/functions/unearthing_biters.lua
@@ -52,7 +52,7 @@ end
 
 local function unearthing_biters(surface, position, amount)
 	if not surface then return end
-    if not surface.valid then return end
+    	if not surface.valid then return end
 	if not position then return end
 	if not position.x then return end
 	if not position.y then return end	
@@ -80,4 +80,4 @@ local function unearthing_biters(surface, position, amount)
 	end		
 end
 
-return unearthing_biters
\ No newline at end of file
+return unearthing_biters