diff --git a/beacon_chain/spec/datatypes/altair.nim b/beacon_chain/spec/datatypes/altair.nim
index d67162d7a..005dc33ca 100644
--- a/beacon_chain/spec/datatypes/altair.nim
+++ b/beacon_chain/spec/datatypes/altair.nim
@@ -36,8 +36,8 @@ import
 
 export base, sets
 
-from ssz_serialization/merkleization import GeneralizedIndex
-export merkleization.GeneralizedIndex
+from ssz_serialization/proofs import GeneralizedIndex
+export proofs.GeneralizedIndex
 
 const
   # https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/altair/beacon-chain.md#incentivization-weights
diff --git a/vendor/nim-ssz-serialization b/vendor/nim-ssz-serialization
index 66745f23b..48f9b7b63 160000
--- a/vendor/nim-ssz-serialization
+++ b/vendor/nim-ssz-serialization
@@ -1 +1 @@
-Subproject commit 66745f23b5d64c79f0f24af95eb63c47a71f8dbf
+Subproject commit 48f9b7b634df9c891e6e9fb4b583d559471330af