diff --git a/zcash_client_backend/src/scan.rs b/zcash_client_backend/src/scan.rs
index 0752f99b1..b6aaec4ac 100644
--- a/zcash_client_backend/src/scan.rs
+++ b/zcash_client_backend/src/scan.rs
@@ -124,15 +124,19 @@ where
     Output: ShieldedOutput<D, COMPACT_NOTE_SIZE>,
 {
     fn dynamic_usage(&self) -> usize {
-        // We don't have a `DynamicUsage` bound on `D::IncomingViewingKey`, `D`, or
+        // We don't have a `DynamicUsage` bound on `A`, `D::IncomingViewingKey`, `D`, or
         // `Output`, and we can't use newtypes because the batch decryption API takes
         // slices. But we know that we don't allocate memory inside either of these, so we
         // just compute the size directly.
-        base_vec_usage(&self.ivks) + base_vec_usage(&self.outputs) + self.repliers.dynamic_usage()
+        base_vec_usage(&self.tags)
+            + base_vec_usage(&self.ivks)
+            + base_vec_usage(&self.outputs)
+            + self.repliers.dynamic_usage()
     }
 
     fn dynamic_usage_bounds(&self) -> (usize, Option<usize>) {
-        let base_usage = base_vec_usage(&self.ivks) + base_vec_usage(&self.outputs);
+        let base_usage =
+            base_vec_usage(&self.tags) + base_vec_usage(&self.ivks) + base_vec_usage(&self.outputs);
         let bounds = self.repliers.dynamic_usage_bounds();
         (
             base_usage + bounds.0,