diff --git a/userspace/engine/lua/parser.lua b/userspace/engine/lua/parser.lua
index 0a78325a..fcae0b01 100644
--- a/userspace/engine/lua/parser.lua
+++ b/userspace/engine/lua/parser.lua
@@ -196,9 +196,9 @@ local G = {
    Identifier = V "idStart" * V "idRest" ^ 0,
    Macro = V "idStart" * V "idRest" ^ 0 * -P ".",
    Int = digit ^ 1,
-   PathString = (alnum + S ",.-_/*?") ^ 1,
+   ArgString = (alnum + S ",.-_/*?~") ^ 1,
    PortRangeString = (V "Int" + S ":,") ^ 1,
-   Index = V "PortRangeString" + V "Int" + V "PathString",
+   Index = V "PortRangeString" + V "Int" + V "ArgString",
    FieldName = V "Identifier" * (P "." + V "Identifier") ^ 1 * (P "[" * V "Index" * P "]") ^ -1,
    Name = C(V "Identifier") * -V "idRest",
    Hex = (P("0x") + P("0X")) * xdigit ^ 1,