diff --git a/Gemfile.lock b/Gemfile.lock
index 85d033f8..47752e27 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -400,7 +400,7 @@ GEM
       unicode-display_width (>= 1.4.0, < 3.0)
     rubocop-ast (1.11.0)
       parser (>= 3.0.1.1)
-    rubocop-rails (2.11.3)
+    rubocop-rails (2.12.2)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.7.0, < 2.0)
@@ -468,7 +468,7 @@ GEM
       concurrent-ruby (~> 1.0)
     uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
-    unicode-display_width (2.0.0)
+    unicode-display_width (2.1.0)
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
diff --git a/app/models/repository.rb b/app/models/repository.rb
index 1c6e8c06..4bc284d6 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -14,7 +14,8 @@ class Repository < ApplicationRecord
            class_name: 'PullRequest',
            primary_key: :github_id,
            foreign_key: :gh_repository_id,
-           inverse_of: :repository)
+           inverse_of: :repository,
+           dependent: :destroy)
 
   has_many :repository_statuses, dependent: :destroy