diff --git a/src/bolero.nf b/src/bolero.nf
index bad6755494241b27b532c103b1bdd1c9f3335e2e..2f3e4131776af14196c9278a0764a13547350a02 100755
--- a/src/bolero.nf
+++ b/src/bolero.nf
@@ -233,7 +233,9 @@ workflow {
         concatenate(tuples_barcode)
       }
       else{
-        tuple_sample = ["Sample", basecall_fast5_gpu.out.pass]
+        basecall_fast5_gpu.out.pass
+          .map{it -> ["Sample", it]}
+          .set{tuple_sample}
         concatenate(tuple_sample)
       }
       control_basecalling(basecall_fast5_gpu.out.sequencing_summary)