diff --git a/README.md b/README.md
index 15c1638..d53b530 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@ Capistrano's default deploy, or can be run in isolation with:
 $ cap production composer:install
 ```
 
-By default it is assumed that you have the composer executable installed and in your
+By default it is assumed that you have the Composer executable installed and in your
 `$PATH` on all target hosts.
 
 ### Configuration
@@ -54,39 +54,33 @@ set :composer_install_flags, '--no-dev --no-interaction --quiet --optimize-autol
 set :composer_roles, :all
 set :composer_working_dir, -> { fetch(:release_path) }
 set :composer_dump_autoload_flags, '--optimize'
-set :composer_download_url, "https://getcomposer.org/installer"
-set :composer_version, '1.0.0-alpha8' #(default: not set)
+set :composer_download_url, 'https://getcomposer.org/installer'
+set :composer_version, '1.0.0-alpha8' # (default: not set)
+set :composer_bin, 'bin/composer.phar' # (default: not set)
+set :composer_php, 'php5' # (default: not set)
 ```
 
-### Installing composer as part of a deployment
+### Installing Composer as part of a deployment
 
-Add the following to `deploy.rb` to manage the installation of composer during
-deployment (composer.phar is install in the shared path).
+To install Composer as part of the deployment, set `:composer_bin` to `:local`.
+This ensures installation of a local `composer.phar` in the shared path.
 
-```ruby
-SSHKit.config.command_map[:composer] = "php #{shared_path.join("composer.phar")}"
-
-namespace :deploy do
-  after :starting, 'composer:install_executable'
-end
-```
-
-### Accessing composer commands directly
+### Accessing Composer commands directly
 
 This library also provides a `composer:run` task which allows access to any
-composer command.
+Composer command.
 
 From the command line you can run
 
 ```bash
-$ cap production composer:run['status','--profile']
+$ cap production composer:run[status,--profile]
 ```
 
-Or from within a rake task using capistrano's `invoke`
+Or from within a rake task using Capistrano's `invoke`
 
 ```ruby
 task :my_custom_composer_task do
-  invoke "composer:run", :update, "--dev --prefer-dist"
+  invoke 'composer:run', :update, '--dev --prefer-dist'
 end
 ```
 
diff --git a/lib/capistrano/tasks/composer.rake b/lib/capistrano/tasks/composer.rake
index 6bee32f..3e36d6e 100644
--- a/lib/capistrano/tasks/composer.rake
+++ b/lib/capistrano/tasks/composer.rake
@@ -1,20 +1,39 @@
 namespace :composer do
-  desc <<-DESC
-    Installs composer.phar to the shared directory
-    In order to use the .phar file, the composer command needs to be mapped:
-      SSHKit.config.command_map[:composer] = "\#{shared_path.join("composer.phar")}"
-    This is best used after deploy:starting:
-      namespace :deploy do
-        after :starting, 'composer:install_executable'
+  task :validate do
+    on release_roles(fetch(:composer_roles)) do
+      composer_php = fetch(:composer_php, capture(:which, 'php'))
+      if composer_php.nil?
+        error 'composer: php not found and composer_php is not set'
+        exit 1
       end
+
+      composer_bin = fetch(:composer_bin, capture(:which, 'composer'))
+      if composer_bin.nil?
+        error 'composer: composer not found and composer_bin is not set'
+        exit 1
+      end
+
+      if composer_bin === :local
+        composer_bin = shared_path.join('composer.phar')
+      end
+
+      SSHKit.config.command_map[:composer] = "#{composer_php} #{composer_bin}"
+    end
+  end
+
+  desc <<-DESC
+    Installs composer.phar to the shared directory.
+
+    When `:composer_bin` is set to `:local`, this task is automatically invoked.
   DESC
   task :install_executable do
     on release_roles(fetch(:composer_roles)) do
       within shared_path do
-        unless test "[", "-e", "composer.phar", "]"
+        unless test "[ -f #{shared_path.join('composer.phar')} ]"
           composer_version = fetch(:composer_version, nil)
-          composer_version_option = composer_version ? "-- --version=#{composer_version}" : ""
-          execute :curl, "-s", fetch(:composer_download_url), "|", :php, composer_version_option
+          composer_version_option = composer_version ? "-- --version=#{composer_version}" : ''
+          execute :curl, '-s', fetch(:composer_download_url),
+            '|', fetch(:composer_php, 'php'), composer_version_option
         end
       end
     end
@@ -30,43 +49,50 @@ namespace :composer do
   end
 
   desc <<-DESC
-        Install the project dependencies via Composer. By default, require-dev \
-        dependencies will not be installed.
+    Install the project dependencies via Composer. By default, require-dev \
+    dependencies will not be installed.
 
-        You can override any of the defaults by setting the variables shown below.
+    You can override any of the defaults by setting the variables shown below.
 
-          set :composer_install_flags, '--no-dev --no-interaction --quiet --optimize-autoloader'
-          set :composer_roles, :all
-    DESC
+      set :composer_install_flags, '--no-dev --no-interaction --quiet --optimize-autoloader'
+      set :composer_roles, :all
+  DESC
   task :install do
-    invoke "composer:run", :install, fetch(:composer_install_flags)
+    invoke 'composer:run', :install, fetch(:composer_install_flags)
   end
 
   task :dump_autoload do
-    invoke "composer:run", :dumpautoload, fetch(:composer_dump_autoload_flags)
+    invoke 'composer:run', :dumpautoload, fetch(:composer_dump_autoload_flags)
   end
 
   desc <<-DESC
-        Run the self-update command for composer.phar
+    Run the self-update command for composer.phar
 
-        You can update to a specific release by setting the variables shown below.
+    You can update to a specific release by setting the variables shown below.
 
-          set :composer_version, '1.0.0-alpha8'
-    DESC
+      set :composer_version, '1.0.0-alpha8'
+  DESC
   task :self_update do
-    invoke "composer:run", :selfupdate, fetch(:composer_version, '')
+    invoke 'composer:run', :selfupdate, fetch(:composer_version, '')
   end
 
   before 'deploy:updated', 'composer:install'
   before 'deploy:reverted', 'composer:install'
 end
 
+Capistrano::DSL.stages.each do |stage|
+  after stage, 'composer:validate'
+  after stage, 'composer:auto_install_executable' do
+    invoke 'composer:install_executable' if fetch(:composer_bin) === :local
+  end
+end
+
 namespace :load do
   task :defaults do
     set :composer_install_flags, '--no-dev --prefer-dist --no-interaction --quiet --optimize-autoloader'
     set :composer_roles, :all
     set :composer_working_dir, -> { fetch(:release_path) }
     set :composer_dump_autoload_flags, '--optimize'
-    set :composer_download_url, "https://getcomposer.org/installer"
+    set :composer_download_url, 'https://getcomposer.org/installer'
   end
 end