diff --git a/app/api/mobile/apis/activities.rb b/app/api/mobile/apis/activities.rb
index 6ce01aac0..4d07c23f8 100644
--- a/app/api/mobile/apis/activities.rb
+++ b/app/api/mobile/apis/activities.rb
@@ -36,7 +36,7 @@ module Mobile
             principal_types = "JournalsForMessage"
             watched_user_ids = User.watched_by(user.id).count == 0 ? " " : ("," + User.watched_by(user.id).map{|u| u.id.to_s }.join(','))
             user_ids = "(" + user.id.to_s + watched_user_ids + ")"
-            watched_user_blog_ids = Blog.select("id").where("author_id in #{user_ids}").count == 0 ? "-1" :Blog.select("id").where("author_id in #{user_ids}").map { |blog| blog.id}.join(",")
+            watched_user_blog_ids = Blog.select("id").where("author_id in #{user_ids}").count == 0 ? " " :Blog.select("id").where("author_id in #{user_ids}").map { |blog| blog.id}.join(",")
             blog_ids = "(" + watched_user_blog_ids + ")"
 
             if container_type == "Course"