diff --git a/spec/bundler/install/gemspecs_spec.rb b/spec/bundler/install/gemspecs_spec.rb
index 7629870db27b47..dee8e547e44a45 100644
--- a/spec/bundler/install/gemspecs_spec.rb
+++ b/spec/bundler/install/gemspecs_spec.rb
@@ -30,7 +30,7 @@
 
   it "should use gemspecs in the system cache when available" do
     gemfile <<-G
-      source "http://localtestserver.gem"
+      source "http://localgemserver.test"
       gem 'myrack'
     G
 
diff --git a/spec/bundler/runtime/inline_spec.rb b/spec/bundler/runtime/inline_spec.rb
index 5be6eef7bd8801..48385b452d8537 100644
--- a/spec/bundler/runtime/inline_spec.rb
+++ b/spec/bundler/runtime/inline_spec.rb
@@ -81,7 +81,7 @@ def script(code, options = {})
 
     script <<-RUBY, artifice: "endpoint"
       gemfile(true) do
-        source "https://notaserver.com"
+        source "https://notaserver.test"
         gem "activesupport", :require => true
       end
     RUBY
@@ -103,7 +103,7 @@ def confirm(msg, newline = nil)
       my_ui = MyBundlerUI.new
       my_ui.level = "confirm"
       gemfile(true, :ui => my_ui) do
-        source "https://notaserver.com"
+        source "https://notaserver.test"
         gem "activesupport", :require => true
       end
     RUBY
@@ -116,7 +116,7 @@ def confirm(msg, newline = nil)
       require 'bundler/inline'
 
       gemfile(true, :quiet => true) do
-        source "https://notaserver.com"
+        source "https://notaserver.test"
         gem "activesupport", :require => true
       end
     RUBY
@@ -363,7 +363,7 @@ def confirm(msg, newline = nil)
 
   it "installs inline gems when a Gemfile.lock is present" do
     gemfile <<-G
-      source "https://notaserver.com"
+      source "https://notaserver.test"
       gem "rake"
     G
 
@@ -397,7 +397,7 @@ def confirm(msg, newline = nil)
 
   it "does not leak Gemfile.lock versions to the installation output" do
     gemfile <<-G
-      source "https://notaserver.com"
+      source "https://notaserver.test"
       gem "rake"
     G
 
diff --git a/spec/bundler/support/artifice/compact_index_creds_diff_host.rb b/spec/bundler/support/artifice/compact_index_creds_diff_host.rb
index 401e8a98d8d9df..282e9c8961388a 100644
--- a/spec/bundler/support/artifice/compact_index_creds_diff_host.rb
+++ b/spec/bundler/support/artifice/compact_index_creds_diff_host.rb
@@ -24,7 +24,7 @@ def protected!
   end
 
   get "/gems/:id" do
-    redirect "http://diffhost.com/no/creds/#{params[:id]}"
+    redirect "http://diffhost.test/no/creds/#{params[:id]}"
   end
 
   get "/no/creds/:id" do
diff --git a/spec/bundler/support/artifice/endpoint_creds_diff_host.rb b/spec/bundler/support/artifice/endpoint_creds_diff_host.rb
index ce30de0a68c5e9..9cbb4de61aa651 100644
--- a/spec/bundler/support/artifice/endpoint_creds_diff_host.rb
+++ b/spec/bundler/support/artifice/endpoint_creds_diff_host.rb
@@ -24,7 +24,7 @@ def protected!
   end
 
   get "/gems/:id" do
-    redirect "http://diffhost.com/no/creds/#{params[:id]}"
+    redirect "http://diffhost.test/no/creds/#{params[:id]}"
   end
 
   get "/no/creds/:id" do
diff --git a/spec/bundler/support/artifice/helpers/endpoint.rb b/spec/bundler/support/artifice/helpers/endpoint.rb
index 329d2d807a8561..5d342c07efb821 100644
--- a/spec/bundler/support/artifice/helpers/endpoint.rb
+++ b/spec/bundler/support/artifice/helpers/endpoint.rb
@@ -27,6 +27,7 @@ def self.all_requests
 
   set :raise_errors, true
   set :show_exceptions, false
+  set :host_authorization, permitted_hosts: [".example.org", ".local", ".repo", ".repo1", ".repo2", ".repo3", ".repo4", ".rubygems.org", ".security", ".source", ".test", "127.0.0.1"]
 
   def call!(*)
     super.tap do
diff --git a/tool/bundler/test_gems.rb b/tool/bundler/test_gems.rb
index bb7d4edb9a2bd9..61377b77be13ea 100644
--- a/tool/bundler/test_gems.rb
+++ b/tool/bundler/test_gems.rb
@@ -8,7 +8,7 @@
 gem "webrick", "~> 1.8"
 gem "rack-test", "~> 2.1"
 gem "compact_index", "~> 0.15.0"
-gem "sinatra", "~> 4.0"
+gem "sinatra", "~> 4.1"
 gem "rake", "~> 13.1"
 gem "builder", "~> 3.2"
 gem "rb_sys"