diff --git a/libraries/shared/factories/storage/transformer.go b/libraries/shared/factories/storage/transformer.go
index f38b06f2..240924bd 100644
--- a/libraries/shared/factories/storage/transformer.go
+++ b/libraries/shared/factories/storage/transformer.go
@@ -42,7 +42,7 @@ func (transformer Transformer) ContractAddress() common.Address {
 }
 
 func (transformer Transformer) Execute(diff utils.StorageDiff) error {
-	metadata, lookupErr := transformer.Mappings.Lookup(diff)
+	metadata, lookupErr := transformer.Mappings.Lookup(diff.StorageKey)
 	if lookupErr != nil {
 		return lookupErr
 	}
diff --git a/libraries/shared/mocks/storage_mappings.go b/libraries/shared/mocks/storage_mappings.go
index b44620ad..d2f681bb 100644
--- a/libraries/shared/mocks/storage_mappings.go
+++ b/libraries/shared/mocks/storage_mappings.go
@@ -17,6 +17,8 @@
 package mocks
 
 import (
+	"github.com/ethereum/go-ethereum/common"
+
 	"github.com/vulcanize/vulcanizedb/libraries/shared/storage/utils"
 	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres"
 )
@@ -27,7 +29,7 @@ type MockMappings struct {
 	LookupErr    error
 }
 
-func (mappings *MockMappings) Lookup(diff utils.StorageDiff) (utils.StorageValueMetadata, error) {
+func (mappings *MockMappings) Lookup(key common.Hash) (utils.StorageValueMetadata, error) {
 	mappings.LookupCalled = true
 	return mappings.Metadata, mappings.LookupErr
 }
diff --git a/libraries/shared/storage/mappings.go b/libraries/shared/storage/mappings.go
index 24740c59..9a534925 100644
--- a/libraries/shared/storage/mappings.go
+++ b/libraries/shared/storage/mappings.go
@@ -27,7 +27,7 @@ import (
 )
 
 type Mappings interface {
-	Lookup(diff utils.StorageDiff) (utils.StorageValueMetadata, error)
+	Lookup(key common.Hash) (utils.StorageValueMetadata, error)
 	SetDB(db *postgres.DB)
 }