diff --git a/rabbit.gemspec b/rabbit.gemspec
index 29896dcb..f73dea70 100644
--- a/rabbit.gemspec
+++ b/rabbit.gemspec
@@ -81,4 +81,5 @@ can see your slide at https://slide.rabbit-shocker.org/ .
   spec.add_runtime_dependency("rouge")
   spec.add_runtime_dependency("rsvg2", ">= 3.1.4")
   spec.add_runtime_dependency("rttool")
+  spec.add_runtime_dependency("drb")
 end