diff --git a/app/controllers/prompts/cards_controller.rb b/app/controllers/prompts/cards_controller.rb
index 77a64178f..bb8c0dfc5 100644
--- a/app/controllers/prompts/cards_controller.rb
+++ b/app/controllers/prompts/cards_controller.rb
@@ -20,7 +20,7 @@ class Prompts::CardsController < ApplicationController
 
     def search_cards
       published_cards
-        .mentioning(params[:filter])
+        .mentioning(params[:filter], board_ids: Current.user.board_ids)
         .reverse_chronologically
         .limit(MAX_RESULTS)
     end
diff --git a/app/models/card/searchable.rb b/app/models/card/searchable.rb
index fc01cce20..8254f5983 100644
--- a/app/models/card/searchable.rb
+++ b/app/models/card/searchable.rb
@@ -4,11 +4,17 @@ module Card::Searchable
   included do
     include ::Searchable
 
-    scope :mentioning, ->(query) do
-      cards = Card.search(query).select(:id).to_sql
-      comments = Comment.search(query).select(:id).to_sql
+    scope :mentioning, ->(query, board_ids:) do
+      query = Search::Query.wrap(query)
 
-      left_joins(:comments).where("cards.id in (#{cards}) or comments.id in (#{comments})").distinct
+      if query.valid?
+        joins("INNER JOIN search_index ON search_index.card_id = cards.id AND search_index.board_id = cards.board_id")
+          .where("search_index.board_id IN (?)", board_ids)
+          .where("MATCH(search_index.content, search_index.title) AGAINST(? IN BOOLEAN MODE)", query.to_s)
+          .distinct
+      else
+        none
+      end
     end
   end
 
diff --git a/app/models/concerns/searchable.rb b/app/models/concerns/searchable.rb
index c94be9193..5620d41c1 100644
--- a/app/models/concerns/searchable.rb
+++ b/app/models/concerns/searchable.rb
@@ -5,18 +5,6 @@ module Searchable
     after_create_commit :create_in_search_index
     after_update_commit :update_in_search_index
     after_destroy_commit :remove_from_search_index
-
-    scope :search, ->(query) do
-      query = Search::Query.wrap(query)
-
-      base = joins("INNER JOIN search_index ON search_index.searchable_type = '#{name}' AND search_index.searchable_id = #{table_name}.id")
-
-      if query.valid?
-        base.where("MATCH(search_index.content, search_index.title) AGAINST(? IN BOOLEAN MODE)", query.to_s)
-      else
-        base.none
-      end
-    end
   end
 
   def reindex
diff --git a/app/models/filter.rb b/app/models/filter.rb
index 005e04e28..c9711c10c 100644
--- a/app/models/filter.rb
+++ b/app/models/filter.rb
@@ -33,7 +33,7 @@ class Filter < ApplicationRecord
       result = result.closed_at_window(closure_window) if closure_window
       result = result.closed_by(closers) if closers.present?
       result = terms.reduce(result) do |result, term|
-        result.mentioning(term)
+        result.mentioning(term, board_ids: creator.board_ids)
       end
 
       result