diff --git a/src/parser.rs b/src/parser.rs
index b5a8454..48d380d 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -21,25 +21,27 @@ pub use source_text::*;
 pub use specify_section::*;
 pub use udp_declaration_and_instantiation::*;
 
-pub type Span<'a> = nom_locate::LocatedSpanEx<&'a str, [u128; 10]>;
+pub const RECURSIVE_FLAG_WORDS: usize = 1;
+pub type Span<'a> = nom_locate::LocatedSpanEx<&'a str, [u128; RECURSIVE_FLAG_WORDS]>;
 
 mod thread_context {
 
+    use crate::parser::RECURSIVE_FLAG_WORDS;
     use std::cell::RefCell;
     use std::collections::HashMap;
 
     pub struct ParserIndex {
-        index: HashMap<&'static str, u32>,
-        allocated: [u128; 10],
+        index: HashMap<&'static str, usize>,
+        allocated: [u128; RECURSIVE_FLAG_WORDS],
     }
 
     impl ParserIndex {
-        pub fn get(&mut self, key: &'static str) -> Option<u32> {
+        pub fn get(&mut self, key: &'static str) -> Option<usize> {
             if let Some(x) = self.index.get(key) {
                 Some(*x)
             } else {
-                for i in 0..1280u32 {
-                    let upper = (i / 128) as usize;
+                for i in 0..128 * RECURSIVE_FLAG_WORDS {
+                    let upper = i / 128;
                     let lower = i % 128;
                     if ((self.allocated[upper] >> lower) & 1) == 0 {
                         let val = 1u128 << lower;
@@ -56,7 +58,7 @@ mod thread_context {
 
     thread_local!(
         pub static PARSER_INDEX: RefCell<ParserIndex> = {
-            RefCell::new(ParserIndex{index: HashMap::new(), allocated: [0;10]})
+            RefCell::new(ParserIndex{index: HashMap::new(), allocated: [0;RECURSIVE_FLAG_WORDS]})
         }
     );
 }
diff --git a/src/parser/utils.rs b/src/parser/utils.rs
index 1db957e..dd9bc2e 100644
--- a/src/parser/utils.rs
+++ b/src/parser/utils.rs
@@ -70,7 +70,7 @@ pub fn symbol<'a>(t: &'a str) -> impl Fn(Span<'a>) -> IResult<Span<'a>, Symbol<'
             );
         }
         let (s, x) = map(ws(tag(t.clone())), |x| Symbol { nodes: x })(s)?;
-        Ok((clear_bit(s), x))
+        Ok((clear_recursive_flags(s), x))
     }
 }
 
@@ -214,15 +214,15 @@ pub fn concat<'a>(a: Span<'a>, b: Span<'a>) -> Option<Span<'a>> {
     }
 }
 
-pub fn check_bit(s: Span, id: u32) -> bool {
-    let upper = (id / 128) as usize;
+pub fn check_recursive_flag(s: Span, id: usize) -> bool {
+    let upper = id / 128;
     let lower = id % 128;
 
     ((s.extra[upper] >> lower) & 1) == 1
 }
 
-pub fn set_bit(s: Span, id: u32, bit: bool) -> Span {
-    let upper = (id / 128) as usize;
+pub fn set_recursive_flag(s: Span, id: usize, bit: bool) -> Span {
+    let upper = id / 128;
     let lower = id % 128;
 
     let val = if bit { 1u128 << lower } else { 0u128 };
@@ -238,12 +238,12 @@ pub fn set_bit(s: Span, id: u32, bit: bool) -> Span {
     }
 }
 
-pub fn clear_bit(s: Span) -> Span {
+pub fn clear_recursive_flags(s: Span) -> Span {
     Span {
         offset: s.offset,
         line: s.line,
         fragment: s.fragment,
-        extra: [0; 10],
+        extra: [0; RECURSIVE_FLAG_WORDS],
     }
 }
 
@@ -252,7 +252,7 @@ pub fn clear_bit(s: Span) -> Span {
 #[cfg(test)]
 macro_rules! parser_test {
     ( $x:expr, $y:expr, $z:pat ) => {
-        let ret = all_consuming($x)(Span::new_extra($y, [0; 10]));
+        let ret = all_consuming($x)(Span::new_extra($y, [0; RECURSIVE_FLAG_WORDS]));
         if let $z = ret {
         } else {
             assert!(false, "{:?}", ret)
diff --git a/sv-parser-derive/src/lib.rs b/sv-parser-derive/src/lib.rs
index f992dfb..db25bdc 100644
--- a/sv-parser-derive/src/lib.rs
+++ b/sv-parser-derive/src/lib.rs
@@ -137,7 +137,7 @@ fn impl_parser(attr: &AttributeArgs, item: &ItemFn) -> TokenStream {
     let checker = quote! {
         if thread_context::PARSER_INDEX.with(|p| {
             if let Some(i) = p.borrow_mut().get(stringify!(#ident)) {
-                return check_bit(s, i);
+                return check_recursive_flag(s, i);
             } else {
                 return false
             }
@@ -154,7 +154,7 @@ fn impl_parser(attr: &AttributeArgs, item: &ItemFn) -> TokenStream {
     let before = quote! {
         let s = thread_context::PARSER_INDEX.with(|p| {
             if let Some(i) = p.borrow_mut().get(stringify!(#ident)) {
-                set_bit(s, i, true)
+                set_recursive_flag(s, i, true)
             } else {
                 if cfg!(feature = "trace") {
                     println!("{:<64} : allocate failed", stringify!(#ident));
@@ -180,7 +180,7 @@ fn impl_parser(attr: &AttributeArgs, item: &ItemFn) -> TokenStream {
     let body = parse_macro_input!(body as Stmt);
 
     let after = quote! {
-        Ok((clear_bit(s), ret))
+        Ok((clear_recursive_flags(s), ret))
     };
     let after: TokenStream = after.into();
     let after = parse_macro_input!(after as Expr);