diff --git a/schala-lang/language/src/ast.rs b/schala-lang/language/src/ast.rs
index 3a973ad..ff813e0 100644
--- a/schala-lang/language/src/ast.rs
+++ b/schala-lang/language/src/ast.rs
@@ -15,11 +15,33 @@ pub struct ItemId {
 }
 
 impl ItemId {
-  pub fn new(n: u32) -> ItemId {
+  fn new(n: u32) -> ItemId {
     ItemId { idx: n }
   }
 }
 
+pub struct ItemIdStore {
+  last_idx: u32
+}
+
+impl ItemIdStore {
+  pub fn new() -> ItemIdStore {
+    ItemIdStore { last_idx: 0 }
+  }
+  /// Always returns an ItemId with internal value zero
+  pub fn new_id() -> ItemId {
+    ItemId { idx: 0 }
+  }
+
+  /// This limits the size of the AST to 2^32 tree elements
+  pub fn fresh(&mut self) -> ItemId {
+    let idx = self.last_idx;
+    self.last_idx += 1;
+    ItemId::new(idx)
+  }
+}
+
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct Meta<T> {
   pub n: T,
diff --git a/schala-lang/language/src/parsing.rs b/schala-lang/language/src/parsing.rs
index ea13cec..d364395 100644
--- a/schala-lang/language/src/parsing.rs
+++ b/schala-lang/language/src/parsing.rs
@@ -183,6 +183,7 @@ pub struct Parser {
   parse_record: Vec<ParseRecord>,
   parse_level: u32,
   restrictions: ParserRestrictions,
+  id_store: ItemIdStore,
 }
 
 struct ParserRestrictions {
@@ -231,7 +232,8 @@ impl Parser {
       token_handler: TokenHandler::new(initial_input),
       parse_record: vec![],
       parse_level: 0,
-      restrictions: ParserRestrictions { no_struct_literal: false }
+      restrictions: ParserRestrictions { no_struct_literal: false },
+      id_store: ItemIdStore::new(),
     }
   }
 
@@ -334,7 +336,7 @@ impl Parser {
         ),
       }
     }
-    Ok(AST { id: ItemId::new(0), statements })
+    Ok(AST { id: self.id_store.fresh(), statements })
   }
 
   /// `statement := expression | declaration`
diff --git a/schala-lang/language/src/parsing/test.rs b/schala-lang/language/src/parsing/test.rs
index 8a95a84..5f720e7 100644
--- a/schala-lang/language/src/parsing/test.rs
+++ b/schala-lang/language/src/parsing/test.rs
@@ -4,7 +4,7 @@ use std::str::FromStr;
 
 use super::tokenize;
 use super::ParseResult;
-use crate::ast::{ItemId, AST, Meta, Expression, Statement, StatementKind, IfExpressionBody, Discriminator, Pattern, PatternLiteral, TypeBody, Enumerator, ForBody, InvocationArgument, FormalParam, PrefixOp, BinOp, QualifiedName};
+use crate::ast::{ItemIdStore, AST, Meta, Expression, Statement, StatementKind, IfExpressionBody, Discriminator, Pattern, PatternLiteral, TypeBody, Enumerator, ForBody, InvocationArgument, FormalParam, PrefixOp, BinOp, QualifiedName};
 use super::Declaration::*;
 use super::Signature;
 use super::TypeIdentifier::*;
@@ -20,12 +20,12 @@ fn parse(input: &str) -> ParseResult<AST> {
 }
 
 macro_rules! parse_test {
-  ($string:expr, $correct:expr) => { 
+  ($string:expr, $correct:expr) => {
     assert_eq!(parse($string).unwrap(), $correct)
   };
 }
 macro_rules! parse_test_wrap_ast {
-  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: ItemId::new(4), statements: vec![$correct] }) }
+  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: ItemIdStore::new_id(), statements: vec![$correct] }) }
 }
 macro_rules! parse_error {
   ($string:expr) => { assert!(parse($string).is_err()) }
@@ -99,7 +99,7 @@ fn parsing_number_literals_and_binexps() {
 
   parse_test! {"3; 4; 4.3",
     AST {
-      id: ItemId::new(0),
+      id: ItemIdStore::new_id(),
       statements: vec![exst!(NatLiteral(3)), exst!(NatLiteral(4)),
       exst!(FloatLiteral(4.3))]
     }
@@ -550,7 +550,7 @@ fn more_advanced_lambdas() {
     r#"fn wahoo() { let a = 10; \(x) { x + a } };
     wahoo()(3) "#,
     AST {
-      id: ItemId::new(0),
+      id: ItemIdStore::new_id(),
       statements: vec![
         exst!(s r"fn wahoo() { let a = 10; \(x) { x + a } }"),
         exst! {