diff --git a/src/protocol/ast.rs b/src/protocol/ast.rs
index b92a35cc3ebf01a92e04de55bbc52babd6d429a8..3978a7d30a793bf1c852e84768971e4221425a25 100644
--- a/src/protocol/ast.rs
+++ b/src/protocol/ast.rs
@@ -1362,6 +1362,8 @@ pub struct SelectCase {
     // ExpressionStatement. Nothing else is allowed by the initial parsing
     pub guard: StatementId,
     pub block: BlockStatementId,
+    // Phase 2: Validation and Linking
+    pub involved_ports: Vec<(CallExpressionId, ExpressionId)>, // call to `get` and its port argument
 }
 
 #[derive(Debug, Clone)]