diff --git a/R/variant_classifier.R b/R/variant_classifier.R
index aab21bccc53856cdae4df69fc4c1e7be63c4fc9b..2a89828ce081f743160543e442ad355a6e280036 100644
--- a/R/variant_classifier.R
+++ b/R/variant_classifier.R
@@ -28,7 +28,8 @@ variant_classifier <- function(
   # Create a table for clustered sequences and filter out clusters with only one sequence
   clustab_tbl <- cluster_tbl_named(clustered_sequences) %>%
     left_join(tibble(seqnames = unlist(map(clustered_sequences, names)),
-                     seqs = as.character(Biostrings:: unlist(clustered_sequences))),
+                     seqs = as.character(unlist(Biostrings::DNAStringSetList(
+                       clustered_sequences)))),
               by = 'seqnames') %>%
     dplyr::filter(clus_size > 1)