diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index bff1794e04983e800c669d9d57ac9d28748e4243..58ab99d88a90f3339eef066f1040ba68a416d58e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -33,7 +33,7 @@ img_cache:
   stage: singularity
   script:
     - mkdir -p ${dir}cache/
-    - cat nextflow.config | grep -oP "container = \K.*" | tr -d "'" | sort | uniq | xargs -P 3 -I {} singularity pull --dir ${dir} 'docker://'{} || true
+    - cat nextflow.config | grep -oP "container = \K.*" | tr -d "'" | sort | uniq | xargs -P 3 -I {} -c "singularity pull --dir ${dir} 'docker://'{} || true"
     - wait
     - echo images cached