diff --git a/modules/nf-core/tcoffee/extractfrompdb/tests/main.nf.test b/modules/nf-core/tcoffee/extractfrompdb/tests/main.nf.test
index c0b4405e4131..71686235246b 100644
--- a/modules/nf-core/tcoffee/extractfrompdb/tests/main.nf.test
+++ b/modules/nf-core/tcoffee/extractfrompdb/tests/main.nf.test
@@ -28,7 +28,7 @@ nextflow_process {
         when {
             process {
                 """
-                input[0] = UNTAR.out.untar.collect{ meta, dir -> file(dir).listFiles().collect().first() }.map{ pdb -> [[ id: 'test'], pdb]}
+                input[0] = UNTAR.out.untar.collect{ meta, dir -> file(dir).listFiles().toList().sort{ file -> file.name }.first() }.map{ pdb -> [[ id: 'test'], pdb]}
                 """
             }
         }