diff --git a/blacklight-spotlight.gemspec b/blacklight-spotlight.gemspec
index f174bb5564..d5f0fe2684 100644
--- a/blacklight-spotlight.gemspec
+++ b/blacklight-spotlight.gemspec
@@ -54,6 +54,7 @@ these collections.)
   s.add_dependency 'signet'
   s.add_dependency 'sir_trevor_rails', '~> 0.5'
   s.add_dependency 'sprockets', '< 4'
+  s.add_dependency 'sprockets-es6'
   s.add_dependency 'tophat'
   s.add_dependency 'underscore-rails', '~> 1.6'