diff --git a/rake/lib/rbenv.rb b/rake/lib/rbenv.rb
index d643b1a6..682bcd04 100644
--- a/rake/lib/rbenv.rb
+++ b/rake/lib/rbenv.rb
@@ -5,6 +5,8 @@ module Rbenv
 
     BREWS = %w{rbenv ruby-build rbenv-bundler rbenv-vars rbenv-gem-rehash}
 
+    GEM_BIN = "/usr/local/opt/rbenv/shims/gem"
+
     def self.bootstrap
         unless self.is_installed?
             BREWS.each { |pkg| Homebrew.install pkg }
@@ -23,12 +25,13 @@ module Rbenv
         unless self.is_version_installed?(version)
             sh_safe "rbenv install #{version}"
         end
-        sh_safe "RBENV_VERSION=#{version} gem install #{gems.join(' ')}"
+        sh_safe "RBENV_VERSION=#{version} #{GEM_BIN} install #{gems.join(' ')}"
     end
 
     def self.update(version)
-        sh_safe "RBENV_VERSION=#{version} gem update"
-        sh_safe "RBENV_VERSION=#{version} gem clean"
+        cmd = self._sudo(version)
+        sh_safe "RBENV_VERSION=#{version} #{cmd} #{GEM_BIN} update"
+        sh_safe "RBENV_VERSION=#{version} #{cmd} #{GEM_BIN} clean"
     end
 
     def self.is_installed?
@@ -43,4 +46,12 @@ module Rbenv
         `ls -1 #{Homebrew.prefix 'rbenv'}/versions`.split("\n")
     end
 
+    def self._sudo(version)
+        if version == 'system'
+            return "sudo"
+        else
+            return ""
+        end
+    end
+
 end