diff --git a/lib/public_activity/renderable.rb b/lib/public_activity/renderable.rb
index ec2174e..20bb8ee 100644
--- a/lib/public_activity/renderable.rb
+++ b/lib/public_activity/renderable.rb
@@ -151,7 +151,11 @@ def prepare_layout(root, layout)
     end
 
     def prepare_parameters(params)
-      @prepared_params ||= self.parameters.with_indifferent_access.merge(params)
+      if self.parameters
+        @prepared_params ||= self.parameters.with_indifferent_access.merge(params)
+      else
+        @prepared_params ||= params
+      end
     end
 
     protected