diff --git a/genomic-processor/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/genomic/GenomicProcessorController.java b/genomic-processor/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/genomic/GenomicProcessorController.java
index f6033fc7..3665cad5 100644
--- a/genomic-processor/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/genomic/GenomicProcessorController.java
+++ b/genomic-processor/src/main/java/edu/harvard/hms/dbmi/avillach/hpds/genomic/GenomicProcessorController.java
@@ -30,7 +30,7 @@ public Mono<VariantMask> queryForPatientMask(@RequestBody DistributableQuery dis
     }
 
     @PostMapping("/variants")
-    public Mono<Collection<String>> queryForVariants(@RequestBody DistributableQuery distributableQuery) {
+    public Mono<Set<String>> queryForVariants(@RequestBody DistributableQuery distributableQuery) {
         return genomicProcessor.getVariantList(distributableQuery);
     }