diff --git a/subworkflows/local/gtdbtk.nf b/subworkflows/local/gtdbtk.nf
index aae4f9ae..21ef25b2 100644
--- a/subworkflows/local/gtdbtk.nf
+++ b/subworkflows/local/gtdbtk.nf
@@ -74,9 +74,8 @@ workflow GTDBTK {
         gtdb_dir = gtdb.listFiles()
         ch_db_for_gtdbtk = Channel
                             .of(gtdb_dir)
-                            .map{['gtdb', it]}
-                            .groupTuple()
-                            .first()
+                            .collect()
+                            .map { ["gtdb", it] }
     } else {
         error("Unsupported object given to --gtdb, database must be supplied as either a directory or a .tar.gz file!")
     }