diff --git a/crates/prometeu-compiler/src/analysis/symbols/mod.rs b/crates/prometeu-compiler/src/analysis/symbols/mod.rs
index b8c81f75..2a1629fc 100644
--- a/crates/prometeu-compiler/src/analysis/symbols/mod.rs
+++ b/crates/prometeu-compiler/src/analysis/symbols/mod.rs
@@ -36,7 +36,7 @@ pub struct Symbol {
     pub decl_span: Span,
 }
 
-#[derive(Debug, Default, Clone)]
+#[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct SymbolArena {
     pub symbols: Vec<Symbol>,
 }
diff --git a/crates/prometeu-compiler/src/frontends/pbs/resolve.rs b/crates/prometeu-compiler/src/frontends/pbs/resolve.rs
index 62760984..1fb612bf 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/resolve.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/resolve.rs
@@ -234,7 +234,7 @@ mod tests {
     use super::*;
     use crate::frontends::pbs::ast::{
         AstArena, BlockNodeArena, CallNodeArena, ExprStmtNodeArena, FileNodeArena, FnDeclNodeArena,
-        IdentNodeArena, NodeId, TypeDeclNodeArena,
+        IdentNodeArena, TypeDeclNodeArena,
     };
     use crate::common::spans::Span;
 
@@ -436,7 +436,7 @@ mod tests {
 
         arena.roots.push(file_id);
 
-        let (symbols, index, ref_index, node_to_symbol, diagnostics) = build_def_index(&arena, 1, &interner, None);
+        let (_symbols, index, ref_index, node_to_symbol, diagnostics) = build_def_index(&arena, 1, &interner, None);
 
         assert!(diagnostics.is_empty(), "Diagnostics should be empty: {:?}", diagnostics);
         
@@ -499,4 +499,64 @@ mod tests {
         assert_eq!(diagnostics[0].code, Some("E_RESOLVE_VISIBILITY".to_string()));
         assert_eq!(diagnostics[0].span, Some(Span::new(0, 50, 62)));
     }
+
+    #[test]
+    fn test_determinism() {
+        let mut arena = AstArena::default();
+        let mut interner = NameInterner::new();
+
+        let target_name = interner.intern("target");
+        let target_body = arena.push(NodeKind::Block(BlockNodeArena { stmts: vec![], tail: None }), Span::new(0, 5, 5));
+        let target_id = arena.push(NodeKind::FnDecl(FnDeclNodeArena {
+            vis: Some("pub".to_string()),
+            name: target_name,
+            params: vec![],
+            ret: None,
+            else_fallback: None,
+            body: target_body,
+        }), Span::new(0, 0, 10));
+
+        let caller_name = interner.intern("caller");
+        let ident_id = arena.push(NodeKind::Ident(IdentNodeArena { name: target_name }), Span::new(0, 50, 56));
+        let call_id = arena.push(NodeKind::Call(CallNodeArena { callee: ident_id, args: vec![] }), Span::new(0, 50, 58));
+        let expr_stmt = arena.push(NodeKind::ExprStmt(ExprStmtNodeArena { expr: call_id }), Span::new(0, 50, 58));
+        let body_id = arena.push(NodeKind::Block(BlockNodeArena { stmts: vec![expr_stmt], tail: None }), Span::new(0, 40, 70));
+
+        let caller_id = arena.push(NodeKind::FnDecl(FnDeclNodeArena {
+            vis: None,
+            name: caller_name,
+            params: vec![],
+            ret: None,
+            else_fallback: None,
+            body: body_id,
+        }), Span::new(0, 30, 80));
+
+        let file_id = arena.push(NodeKind::File(FileNodeArena {
+            imports: vec![],
+            decls: vec![target_id, caller_id],
+        }), Span::new(0, 0, 100));
+
+        arena.roots.push(file_id);
+
+        let run1 = build_def_index(&arena, 1, &interner, None);
+        let run2 = build_def_index(&arena, 1, &interner, None);
+
+        // runX is (SymbolArena, DefIndex, RefIndex, NodeToSymbol, Vec<Diagnostic>)
+        
+        let json1_symbols = serde_json::to_string(&run1.0).unwrap();
+        let json2_symbols = serde_json::to_string(&run2.0).unwrap();
+        assert_eq!(json1_symbols, json2_symbols, "SymbolArena should be deterministic");
+
+        let json1_refs = serde_json::to_string(&run1.2).unwrap();
+        let json2_refs = serde_json::to_string(&run2.2).unwrap();
+        assert_eq!(json1_refs, json2_refs, "RefIndex should be deterministic");
+
+        let json1_node_to_symbol = serde_json::to_string(&run1.3).unwrap();
+        let json2_node_to_symbol = serde_json::to_string(&run2.3).unwrap();
+        assert_eq!(json1_node_to_symbol, json2_node_to_symbol, "NodeToSymbol should be deterministic");
+
+        let json1_diags = serde_json::to_string(&run1.4).unwrap();
+        let json2_diags = serde_json::to_string(&run2.4).unwrap();
+        assert_eq!(json1_diags, json2_diags, "Diagnostics should be deterministic");
+    }
 }
diff --git a/test-cartridges/canonical/golden/program.pbc b/test-cartridges/canonical/golden/program.pbc
index 666448e9..b06b91ca 100644
Binary files a/test-cartridges/canonical/golden/program.pbc and b/test-cartridges/canonical/golden/program.pbc differ
diff --git a/test-cartridges/test01/cartridge/program.pbc b/test-cartridges/test01/cartridge/program.pbc
index eafefd12..dbb0922a 100644
Binary files a/test-cartridges/test01/cartridge/program.pbc and b/test-cartridges/test01/cartridge/program.pbc differ