diff --git a/src/protocol/eval/executor.rs b/src/protocol/eval/executor.rs
index f95a61b3c62f75ac315120a8b9dfa3baac09d2a3..2e9946bb6cf62cb6001b1472e3a00f8fe9cae134 100644
--- a/src/protocol/eval/executor.rs
+++ b/src/protocol/eval/executor.rs
@@ -584,10 +584,12 @@ impl Prompt {
                                         unreachable!("executor calling 'get' on value {:?}", value)
                                     };
 
-                                    match ctx.get(port_id, &mut self.store) {
+                                    match ctx.get(port_id) {
                                         Some(result) => {
-                                            // We have the result
-                                            cur_frame.expr_values.push_back(result)
+                                            // We have the result. Merge the `ValueGroup` with the
+                                            // stack/heap storage.
+                                            debug_assert_eq!(result.values.len(), 1);
+                                            result.into_stack(&mut cur_frame.expr_values, &mut self.store);
                                         },
                                         None => {
                                             // Don't have the result yet, prepare the expression to
@@ -639,7 +641,7 @@ impl Prompt {
                                     let port_id = match port_value_deref {
                                         Value::Input(port_id) => port_id,
                                         Value::Output(port_id) => port_id,
-                                        _ => unreachable!("executor calling 'fires' on value {:?}", value),
+                                        _ => unreachable!("executor calling 'fires' on value {:?}", port_value_deref),
                                     };
 
                                     match ctx.fires(port_id) {