diff --git a/internal/repository/index.go b/internal/repository/index.go
index 8978b60d5..767357eb3 100644
--- a/internal/repository/index.go
+++ b/internal/repository/index.go
@@ -294,6 +294,8 @@ func (idx *Index) EachByPack(ctx context.Context, packBlacklist restic.IDSet) <-
 					result.Blobs = append(result.Blobs, idx.toPackedBlob(e, restic.BlobType(typ)).Blob)
 				}
 			}
+			// allow GC once entry is no longer necessary
+			byPack[packID] = nil
 			select {
 			case <-ctx.Done():
 				return
diff --git a/internal/repository/master_index.go b/internal/repository/master_index.go
index 955080e82..058a3a662 100644
--- a/internal/repository/master_index.go
+++ b/internal/repository/master_index.go
@@ -458,6 +458,8 @@ func (mi *MasterIndex) ListPacks(ctx context.Context, packs restic.IDSet) <-chan
 
 			// pass on packs
 			for packID, pbs := range packBlob {
+				// allow GC
+				packBlob[packID] = nil
 				select {
 				case out <- restic.PackBlobs{PackID: packID, Blobs: pbs}:
 				case <-ctx.Done():