diff --git a/compress_pipeline.cwl b/compress_pipeline.cwl
index fb1aae27b7b4f26786cdedb8260b249c3e2226bf..e82c8f3c1b113802a53f68d84ab832b1d985587e 100644
--- a/compress_pipeline.cwl
+++ b/compress_pipeline.cwl
@@ -108,3 +108,4 @@ steps:
     'sbg:y': 132
 requirements:
   - class: ScatterFeatureRequirement
+  - class: StepInputExpressionRequirement