diff --git a/workflow/schema/config.schema.yaml b/workflow/schema/config.schema.yaml
index 440d9c8c..28a2c61b 100644
--- a/workflow/schema/config.schema.yaml
+++ b/workflow/schema/config.schema.yaml
@@ -105,7 +105,8 @@ properties:
       treatment_var:
         type: string
       collapse_replicates:
-        type: boolean
+        type: string
+        enum: ["T", "F"]
       technical_control:
         type: string
       reference_rna: