diff --git a/modules/local/ciriquant/de/main.nf b/modules/local/ciriquant/de/main.nf
index 0e3eb14a..3795151e 100644
--- a/modules/local/ciriquant/de/main.nf
+++ b/modules/local/ciriquant/de/main.nf
@@ -8,8 +8,8 @@ process CIRIQUANT_DE {
     tuple val(meta), path(library), path(expression), path(gene)
 
     output:
-    tuple val(meta), path("${circ_path}"), emit: circ
-    tuple val(meta), path("${gene_path}"), emit: gene
+    tuple val(meta), path("${circ_path}"), emit: circ, optional: true
+    tuple val(meta), path("${gene_path}"), emit: gene, optional: true
     path "versions.yml", emit: versions
 
     when: