diff --git a/assets/.lua/csexp.lua b/assets/.lua/csexp.lua
index b321b30..41d3b69 100644
--- a/assets/.lua/csexp.lua
+++ b/assets/.lua/csexp.lua
@@ -17,7 +17,7 @@ local function _parse(str, init)
 		end
 	else
 		local pos = init
-		local len_str = string.match(str, "^[1-9]%d*", pos)
+		local len_str = string.match(str, "^%d+", pos)
 		if not len_str then
 			error(string.format("expected '(' or atom at index %d", pos))
 		end