diff --git a/schala-lang/language/src/ast/visitor.rs b/schala-lang/language/src/ast/visitor.rs
index 161a217..02c9b8a 100644
--- a/schala-lang/language/src/ast/visitor.rs
+++ b/schala-lang/language/src/ast/visitor.rs
@@ -92,8 +92,8 @@ pub fn walk_expression<V: ASTVisitor>(v: &mut V, expr: &Expression) {
                 walk_expression(v, f);
                 for arg in arguments.iter() {
                     match arg {
-                        InvocationArgument::Positional(expr) => walk_expression(v, expr),
-                        InvocationArgument::Keyword { expr, .. } => walk_expression(v, expr), //TODO maybe I can combine this pattern
+                        InvocationArgument::Positional(expr) | InvocationArgument::Keyword { expr, .. } =>
+                            walk_expression(v, expr),
                         _ => (),
                     }
                 }
diff --git a/schala-lang/language/src/symbol_table/mod.rs b/schala-lang/language/src/symbol_table/mod.rs
index 4e9a948..071ba2a 100644
--- a/schala-lang/language/src/symbol_table/mod.rs
+++ b/schala-lang/language/src/symbol_table/mod.rs
@@ -147,6 +147,7 @@ pub struct SymbolTable {
     fqsn_to_symbol: HashMap<Fqsn, Rc<Symbol>>,
 
     id_to_symbol: HashMap<ItemId, Rc<Symbol>>,
+    def_to_symbol: HashMap<DefId, Rc<Symbol>>,
 }
 
 impl SymbolTable {
@@ -159,6 +160,7 @@ impl SymbolTable {
 
             fqsn_to_symbol: HashMap::new(),
             id_to_symbol: HashMap::new(),
+            def_to_symbol: HashMap::new(),
         }
     }
 
@@ -184,9 +186,8 @@ impl SymbolTable {
         self.id_to_symbol.get(id).map(|s| s.as_ref())
     }
 
-    //TODO optimize this
     pub fn lookup_symbol_by_def(&self, def: &DefId) -> Option<&Symbol> {
-        self.id_to_symbol.iter().find(|(_, sym)| sym.def_id == *def).map(|(_, sym)| sym.as_ref())
+        self.def_to_symbol.get(def).map(|s| s.as_ref())
     }
 
     #[allow(dead_code)]
@@ -205,7 +206,8 @@ impl SymbolTable {
         let symbol = Rc::new(Symbol { fully_qualified_name: fqsn.clone(), spec, def_id });
         self.symbol_trie.insert(&fqsn);
         self.fqsn_to_symbol.insert(fqsn, symbol.clone());
-        self.id_to_symbol.insert(*id, symbol);
+        self.id_to_symbol.insert(*id, symbol.clone());
+        self.def_to_symbol.insert(def_id, symbol);
     }
 }