diff --git a/java/src/org/broadinstitute/sting/gatk/arguments/GATKArgumentCollection.java b/java/src/org/broadinstitute/sting/gatk/arguments/GATKArgumentCollection.java
index 80d3c6b3f..816d2c71d 100755
--- a/java/src/org/broadinstitute/sting/gatk/arguments/GATKArgumentCollection.java
+++ b/java/src/org/broadinstitute/sting/gatk/arguments/GATKArgumentCollection.java
@@ -158,7 +158,7 @@ public class GATKArgumentCollection {
     @Argument(fullName = "disable_experimental_sharding",shortName="ds", doc="Disable the experimental sharding strategy.", required = false)
     public boolean disableExperimentalSharding = false;
 
-    @Element(required = false)
+    @ElementList(required = false)
     @Argument(fullName = "read_group_black_list", shortName="rgbl", doc="Filters out read with read groups matching <TAG>:<SUBSTRING> or a .txt file containing the filter strings one per line.", required = false)
     public List<String> readGroupBlackList = null;