diff --git a/src/protocol/eval/value.rs b/src/protocol/eval/value.rs
index c4c5060485d669df5943ff6af48090d89b0f604e..97a9f0e8b47f17bdf8d9a75297b8256b2515bea7 100644
--- a/src/protocol/eval/value.rs
+++ b/src/protocol/eval/value.rs
@@ -261,6 +261,14 @@ impl ValueGroup {
         }
     }
 
+    /// Retrieves a mutable reference to the value given its ValueId.
+    pub(crate) fn get_value_mut(&mut self, id: ValueId) -> &mut Value {
+        match id {
+            ValueId::Stack(pos) => return &mut self.values[pos as usize],
+            ValueId::Heap(heap_pos, pos) => return &mut self.regions[heap_pos as usize][pos as usize],
+        }
+    }
+
     fn provide_value(&self, value: &Value, to_store: &mut Store) -> Value {
         if let Some(from_heap_pos) = value.get_heap_pos() {
             let from_heap_pos = from_heap_pos as usize;