diff --git a/eth2/utils/bls/src/aggregate_signature.rs b/eth2/utils/bls/src/aggregate_signature.rs
index f446ce71ee..8c7ae5222e 100644
--- a/eth2/utils/bls/src/aggregate_signature.rs
+++ b/eth2/utils/bls/src/aggregate_signature.rs
@@ -38,7 +38,8 @@ impl AggregateSignature {
 
     /// Add (aggregate) another `AggregateSignature`.
     pub fn add_aggregate(&mut self, agg_signature: &AggregateSignature) {
-        self.0.add_aggregate(&agg_signature.0)
+        self.aggregate_signature
+            .add_aggregate(&agg_signature.aggregate_signature)
     }
 
     /// Verify the `AggregateSignature` against an `AggregatePublicKey`.