diff --git a/cmd/pow/cmd/prepare/prepare.go b/cmd/pow/cmd/prepare/prepare.go
index ff2c2d8d..30ee57c4 100644
--- a/cmd/pow/cmd/prepare/prepare.go
+++ b/cmd/pow/cmd/prepare/prepare.go
@@ -482,6 +482,10 @@ func dagify(ctx context.Context, dagService ipld.DAGService, path string, quiet
 			aggregatedFiles = append(aggregatedFiles, aggregatedFile{Name: p, Cid: dcid.String()})
 			return err
 		})
+		if err != nil {
+			return cid.Undef, nil, fmt.Errorf("walking the target folder: %s", err)
+		}
+
 		dataCid, err = aggregator.Aggregate(ctx, dagService, lst)
 		if err != nil {
 			return cid.Undef, nil, fmt.Errorf("aggregating: %s", err)
diff --git a/cmd/pow/cmd/prepare/prepare_test.go b/cmd/pow/cmd/prepare/prepare_test.go
index c58d0c38..ec94a918 100644
--- a/cmd/pow/cmd/prepare/prepare_test.go
+++ b/cmd/pow/cmd/prepare/prepare_test.go
@@ -22,9 +22,9 @@ func TestOfflinePreparation(t *testing.T) {
 		size int
 		json string
 	}{
-		{size: 10000, json: `{"piece_size":16384,"piece_cid":"baga6ea4seaqjuk4uh5g7cu5znbvrr7wvfsn2l3xj47rbymvi63uiiroya44lkiy"}`},
-		{size: 1000, json: `{"piece_size":2048,"piece_cid":"baga6ea4seaqadahcx4ct54tlbvgkqlhmif7kxxkvxz3yf3vr2e4puhvsxdbrgka"}`},
-		{size: 100, json: `{"piece_size":256,"piece_cid":"baga6ea4seaqd4hgfl6texpf377k7igx2ga2mfwn3lb4c4kdpaq3g3oao2yftuki"}`},
+		{size: 10000, json: `{"payload_cid":"QmRP8TCp9bthhzLACAao6mh8cfLypqXncdNbzuPtuqFYP7","piece_size":16384,"piece_cid":"baga6ea4seaqjuk4uh5g7cu5znbvrr7wvfsn2l3xj47rbymvi63uiiroya44lkiy"}`},
+		{size: 1000, json: `{"payload_cid":"QmQRAjpSLWziADGz8p5ezxTguFNn18yYbSnduKqMrbJ93c","piece_size":2048,"piece_cid":"baga6ea4seaqadahcx4ct54tlbvgkqlhmif7kxxkvxz3yf3vr2e4puhvsxdbrgka"}`},
+		{size: 100, json: `{"payload_cid":"QmY6zHswPvyZkAyxwM9uup1DDPb67hZqChv8hnyu4MrFWk","piece_size":256,"piece_cid":"baga6ea4seaqd4hgfl6texpf377k7igx2ga2mfwn3lb4c4kdpaq3g3oao2yftuki"}`},
 	}
 
 	for _, test := range testCases {