diff --git a/installer/install.sh b/installer/install.sh
--- a/installer/install.sh
+++ b/installer/install.sh
@@ -2,7 +2,8 @@
 
 echo "This script will install and configure Cafe grader."
 
-echo "This will install Ruby 1.9.2 under rvm"
+RUBY_VERSION=2.1.2
+echo "This will install Ruby $RUBY_VERSION under RVM"
 
 echo "Installing required apts"
 
@@ -19,10 +20,10 @@
 curl -k -L https://get.rvm.io | bash -s stable
 source ~/.rvm/scripts/rvm
 
-echo "Installing Ruby 2.1.2 in RVM"
+echo "Installing Ruby $RUBY_VERSION in RVM"
 
-rvm install 2.1.2
-rvm use 2.1.2
+rvm install $RUBY_VERSION
+rvm use $RUBY_VERSION
 
 echo "Fetching Cafe Grader from Git repositories"
 
@@ -160,10 +161,8 @@
 MACHINE_TYPE=`uname -m`
 if [ ${MACHINE_TYPE} == 'x86_64' ]; then
   gcc -std=c99 -o scripts/std-script/box scripts/std-script/box64-new.c
-  # 64-bit stuff here
 else
   g++ -o scripts/std-script/box scripts/std-script/box.cc
-  # 32-bit stuff here
 fi
 
 
diff --git a/new_problem b/new_problem
--- a/new_problem
+++ b/new_problem
@@ -1,4 +1,4 @@
-#!/usr/bin/ruby
+#!/usr/bin/env ruby
 
 # new_problem:
 #  * creates a directory for a problem in the current directory,
diff --git a/templates/check_wrapper b/templates/check_wrapper
--- a/templates/check_wrapper
+++ b/templates/check_wrapper
@@ -1,4 +1,4 @@
-#!/usr/bin/ruby
+#!/usr/bin/env ruby
 
 #
 # This is a check script wrapper.  It read all required information
diff --git a/test/data/ev/test_memory/script/check b/test/data/ev/test_memory/script/check
--- a/test/data/ev/test_memory/script/check
+++ b/test/data/ev/test_memory/script/check
@@ -1,4 +1,4 @@
-#!/usr/bin/ruby
+#!/usr/bin/env ruby
 
 problem_home = ENV['PROBLEM_HOME']
 require "#{problem_home}/script/test_dsl.rb"
diff --git a/test/data/ev/test_normal/script/check b/test/data/ev/test_normal/script/check
--- a/test/data/ev/test_normal/script/check
+++ b/test/data/ev/test_normal/script/check
@@ -1,4 +1,4 @@
-#!/usr/bin/ruby
+#!/usr/bin/env ruby
 
 problem_home = ENV['PROBLEM_HOME']
 require "#{problem_home}/script/test_dsl.rb"
diff --git a/test/data/ev/test_timeout/script/check b/test/data/ev/test_timeout/script/check
--- a/test/data/ev/test_timeout/script/check
+++ b/test/data/ev/test_timeout/script/check
@@ -1,4 +1,4 @@
-#!/usr/bin/ruby
+#!/usr/bin/env ruby
 
 problem_home = ENV['PROBLEM_HOME']
 require "#{problem_home}/script/test_dsl.rb"
diff --git a/test/engine_spec.rb b/test/engine_spec.rb
--- a/test/engine_spec.rb
+++ b/test/engine_spec.rb
@@ -202,7 +202,7 @@
                     :grader_comment= => '',
                     :running_stat= => /0.0\d* sec./, 
                     :output_file_name= => lambda { |fname|
-                      File.exists?(fname).should be_true
+                      File.exists?(fname).should be true
                     },
                     :running_time= => nil,
                     :exit_status= => nil,
@@ -226,7 +226,7 @@
                     :exit_status= => nil,
                     :memory_usage= => nil,
                     :save => nil})
-    File.exists?(@config.user_result_dir + "/test_request/test_normal/test_cases/1/input-1.txt").should be_false
+    File.exists?(@config.user_result_dir + "/test_request/test_normal/test_cases/1/input-1.txt").should be false
   end
 
   it "should compile test request with error and report compilation error" do
@@ -255,7 +255,7 @@
                     :grader_comment= => '',
                     :running_stat= => /[Ee]xit.*status.*10.*0\.0\d* sec/m,
                     :output_file_name= => lambda { |fname|
-                      File.exists?(fname).should be_true
+                      File.exists?(fname).should be true
                     },
                     :running_time= => nil,
                     :exit_status= => /10/,
@@ -275,7 +275,7 @@
                     :grader_comment= => '',
                     :running_stat= => nil,
                     :output_file_name= => lambda { |fname|
-                      File.exists?(fname).should be_true
+                      File.exists?(fname).should be true
                     },
                     :running_time= => lambda { |t|
                       (t>=0.14) and (t<=0.16)