diff --git a/schala-lang/language/src/ast.rs b/schala-lang/language/src/ast.rs
index 491776a..3a973ad 100644
--- a/schala-lang/language/src/ast.rs
+++ b/schala-lang/language/src/ast.rs
@@ -1,6 +1,7 @@
 use std::rc::Rc;
 use std::convert::From;
 
+use crate::derivative::Derivative;
 use crate::typechecking::TypeData;
 use crate::symbol_table::FullyQualifiedSymbolName;
 
@@ -52,8 +53,11 @@ impl From<Expression> for Meta<Expression> {
   }
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Derivative, Debug)]
+#[derivative(PartialEq)]
 pub struct AST {
+  #[derivative(PartialEq="ignore")]
+  pub id: ItemId,
   pub statements: Vec<Meta<Statement>>
 }
 
diff --git a/schala-lang/language/src/parsing.rs b/schala-lang/language/src/parsing.rs
index e601ac3..ea13cec 100644
--- a/schala-lang/language/src/parsing.rs
+++ b/schala-lang/language/src/parsing.rs
@@ -334,7 +334,7 @@ impl Parser {
         ),
       }
     }
-    Ok(AST { statements })
+    Ok(AST { id: ItemId::new(0), statements })
   }
 
   /// `statement := expression | declaration`
diff --git a/schala-lang/language/src/parsing/test.rs b/schala-lang/language/src/parsing/test.rs
index 06fd114..8a95a84 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::{AST, Meta, Expression, Statement, StatementKind, IfExpressionBody, Discriminator, Pattern, PatternLiteral, TypeBody, Enumerator, ForBody, InvocationArgument, FormalParam, PrefixOp, BinOp, QualifiedName};
+use crate::ast::{ItemId, 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::*;
@@ -25,7 +25,7 @@ macro_rules! parse_test {
   };
 }
 macro_rules! parse_test_wrap_ast {
-  ($string:expr, $correct:expr) => { parse_test!($string, AST { statements: vec![$correct] }) }
+  ($string:expr, $correct:expr) => { parse_test!($string, AST { id: ItemId::new(4), statements: vec![$correct] }) }
 }
 macro_rules! parse_error {
   ($string:expr) => { assert!(parse($string).is_err()) }
@@ -99,6 +99,7 @@ fn parsing_number_literals_and_binexps() {
 
   parse_test! {"3; 4; 4.3",
     AST {
+      id: ItemId::new(0),
       statements: vec![exst!(NatLiteral(3)), exst!(NatLiteral(4)),
       exst!(FloatLiteral(4.3))]
     }
@@ -549,6 +550,7 @@ fn more_advanced_lambdas() {
     r#"fn wahoo() { let a = 10; \(x) { x + a } };
     wahoo()(3) "#,
     AST {
+      id: ItemId::new(0),
       statements: vec![
         exst!(s r"fn wahoo() { let a = 10; \(x) { x + a } }"),
         exst! {