diff --git a/modules/local/hicstuff/build_matrix.nf b/modules/local/hicstuff/build_matrix.nf
index 0036dcb20d1134d4abbf5858d1a5509af2f9aa80..c81df964907a22f66c3f2bd3caaca5d09e3863ad 100644
--- a/modules/local/hicstuff/build_matrix.nf
+++ b/modules/local/hicstuff/build_matrix.nf
@@ -1,19 +1,21 @@
 process BUILD_MATRIX {
-    tag '$idx_pairs'
+    tag "$idx_pairs"
     label 'process_single'
 
     conda "conda-forge::python=3.9 conda-forge::biopython=1.80 conda-forge::numpy=1.22.3 conda-forge::matplotlib=3.6.3 conda-forge::pandas=1.5.3"
     container = "lbmc/hicstuff:3.1.3"
 
     input:
-    tuple val(meta), path(idx_pairs)
+    tuple val(meta1), path(idx_pairs)
     tuple val(meta), path(fragments_list)
 
     output:
-    tuple val(meta), path("abs_fragments_contacts_weighted.txt"), emit: matrix
+    tuple val(meta), path("${meta1.id}_fragments_contacts_weighted.txt"), emit: matrix
 
     script:
     """
     hicstuff_build_matrix.py -p ${idx_pairs} -f ${fragments_list} -t graal -o abs_fragments_contacts_weighted.txt
+
+    mv abs_fragments_contacts_weighted.txt ${meta1.id}_fragments_contacts_weighted.txt
     """
 }