diff --git a/lib/solidus_dev_support/templates/extension/bin/sandbox.tt b/lib/solidus_dev_support/templates/extension/bin/sandbox.tt
index e7a89915..389af2bb 100755
--- a/lib/solidus_dev_support/templates/extension/bin/sandbox.tt
+++ b/lib/solidus_dev_support/templates/extension/bin/sandbox.tt
@@ -30,7 +30,8 @@ echo "~~~> Removing the old sandbox"
 rm -rf ./sandbox
 
 echo "~~~> Creating a pristine Rails app"
-rails new sandbox \
+rails_version=`bundle exec ruby -e'require "rails"; puts Rails.version'`
+rails _${rails_version}_ new sandbox \
   --database="${DB:-sqlite3}" \
   --skip-git \
   --skip-keeps \
diff --git a/spec/features/create_extension_spec.rb b/spec/features/create_extension_spec.rb
index 869c1eba..330025d4 100644
--- a/spec/features/create_extension_spec.rb
+++ b/spec/features/create_extension_spec.rb
@@ -96,11 +96,9 @@ def check_create_extension
 
   def check_bundle_install
     cd(install_path) do
-      open('Gemfile', 'a') { |f| f.puts "gem 'solidus_dev_support', path: '../../..'" }
+      open('Gemfile', 'a') { |f| f.puts "gem 'solidus_dev_support', path: '../..'" }
     end
 
-    expect { bundle_install }.to raise_error(command_failed_error, /invalid gemspec/)
-
     # Update gemspec with the required fields
     gemspec_path = install_path.join(gemspec_name)
     gemspec = gemspec_path.read.lines
@@ -139,9 +137,7 @@ def check_run_specs
 
   def check_sandbox
     cd(install_path) do
-      # rubocop:disable Lint/InterpolationCheck
       command = 'bin/rails-sandbox runner "puts %{The version of SolidusTestExtension is #{SolidusTestExtension::VERSION}}"'
-      # rubocop:enable Lint/InterpolationCheck
 
       first_run_output = sh(command)
       expect(first_run_output).to include("Creating the sandbox app...")