diff --git a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
index 37006ca..5b4f172 100644
--- a/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
+++ b/src/main/scala/com/googlesource/gerrit/plugins/analytics/Contributors.scala
@@ -180,7 +180,7 @@
   def apply(statisticsHandler: Statistics)(uca: AggregatedUserCommitActivity)
   : Iterable[UserActivitySummary] = {
 
-    statisticsHandler.forCommits(uca.getIds: _*).map { stat =>
+    statisticsHandler.forCommits(uca.getIds.toIndexedSeq: _*).map { stat =>
       val maybeBranches =
         uca.key.branch.fold(Array.empty[String])(Array(_))