diff --git a/app/controllers/public/conference_feedbacks_controller.rb b/app/controllers/public/conference_feedbacks_controller.rb
index 486dec6..7f42f31 100644
--- a/app/controllers/public/conference_feedbacks_controller.rb
+++ b/app/controllers/public/conference_feedbacks_controller.rb
@@ -4,27 +4,27 @@ class Public::ConferenceFeedbacksController < Public::ApplicationController
     @unrated_events = @conference.events
       .joins(:proposition).approved
       .joins("LEFT JOIN feedbacks ON feedbacks.feedback_receiving_id = events.id AND feedbacks.feedback_receiving_type = 'Event'")
-      .where("feedbacks.session_id != ? OR feedbacks.id IS NULL", session.id).distinct
+      .where("feedbacks.session_id != ? OR feedbacks.id IS NULL", session.id.to_s).distinct
 
     @rated_events = @conference.events
       .joins(:proposition).approved
       .joins(:feedbacks)
-      .where(feedbacks: {session_id: session.id}).distinct
+      .where(feedbacks: {session_id: session.id.to_s}).distinct
   end
 
   def new
-    if current_conference.feedbacks.where(session_id: session.id).exists?
-      @feedback = current_conference.feedbacks.where(session_id: session.id).order(updated_at: :asc).last
+    if current_conference.feedbacks.where(session_id: session.id.to_s).exists?
+      @feedback = current_conference.feedbacks.where(session_id: session.id.to_s).order(updated_at: :asc).last
     else
       @feedback = current_conference.feedbacks.build
-      @feedback.author_email = Feedback.where(session_id: session.id).order(updated_at: :asc).last.try(:author_email)
+      @feedback.author_email = Feedback.where(session_id: session.id.to_s).order(updated_at: :asc).last.try(:author_email)
     end
   end
 
   def create
     @feedback = current_conference.feedbacks.build(feedback_params)
     @feedback.ip_address = request.remote_ip
-    @feedback.session_id = session.id
+    @feedback.session_id = session.id.to_s
 
     if @feedback.save
       flash[:notice] = I18n.t("public.conference_feedbacks.new.success")
diff --git a/app/controllers/public/event_feedbacks_controller.rb b/app/controllers/public/event_feedbacks_controller.rb
index 2b7bd16..0e3e7b2 100644
--- a/app/controllers/public/event_feedbacks_controller.rb
+++ b/app/controllers/public/event_feedbacks_controller.rb
@@ -1,17 +1,17 @@
 class Public::EventFeedbacksController < Public::ApplicationController
   def new
-    if event.feedbacks.where(session_id: session.id).exists?
-      @feedback = event.feedbacks.where(session_id: session.id).order(updated_at: :asc).last
+    if event.feedbacks.where(session_id: session.id.to_s).exists?
+      @feedback = event.feedbacks.where(session_id: session.id.to_s).order(updated_at: :asc).last
     else
       @feedback = event.feedbacks.build
-      @feedback.author_email = Feedback.where(session_id: session.id).order(updated_at: :asc).last.try(:author_email)
+      @feedback.author_email = Feedback.where(session_id: session.id.to_s).order(updated_at: :asc).last.try(:author_email)
     end
   end
 
   def create
     @feedback = event.feedbacks.build(feedback_params)
     @feedback.ip_address = request.remote_ip
-    @feedback.session_id = session.id
+    @feedback.session_id = session.id.to_s
 
     if @feedback.save
       flash[:notice] = I18n.t("public.event_feedbacks.new.success")
diff --git a/lib/initfest/views/public/conference_feedbacks/index.html.slim b/lib/initfest/views/public/conference_feedbacks/index.html.slim
index 5a36d9b..953a2bf 100644
--- a/lib/initfest/views/public/conference_feedbacks/index.html.slim
+++ b/lib/initfest/views/public/conference_feedbacks/index.html.slim
@@ -5,7 +5,7 @@ h1.entry-title = t('.feedback_for_the_conference')
 p = t('.feedback_incentive')
 
 ul
-  - if @conference.feedbacks.where(session_id: session.id).exists?
+  - if @conference.feedbacks.where(session_id: session.id.to_s).exists?
     li = link_to t('.change_general_feedback_for', title: @conference.title), new_conference_feedback_path
   - else
     li = link_to t('.general_feedback_for', title: @conference.title), new_conference_feedback_path