diff --git a/src/main.nf b/src/main.nf
index 2c6002524a2ff254f252173e5ecf3c30f55193fa..e65bd25e93ccdcbe30425a62037a8672b86f6a19 100644
--- a/src/main.nf
+++ b/src/main.nf
@@ -31,7 +31,7 @@ workflow {
   SUBSAMPLE_READ(fastq.r1.mix(fastq.r2))
   SPLIT(SUBSAMPLE_READ.out.fastq)
   FASTKMERS(SPLIT.out.fastq.transpose())
-  MERGEKMER(FASTKMERS.out.csv.groupTuple())
+  MERGEKMER(FASTKMERS.out.csv.map{it -> [[it[0][0], it[0][1], it[0][2]], it[1]]}.groupTuple())
   COLLATEKMER(MERGEKMER.out.csv.map{it -> [it[0].specie, it[1]] }.groupTuple())
   KMERCLUST_LOAD(COLLATEKMER.out.csv, params_csv.collect())
   KMERCLUST_BOOT(Channel.of(1..params.bootstrap).combine(KMERCLUST_LOAD.out.rdata))