diff --git a/app/models/token.rb b/app/models/token.rb
index 0e8c2c3e2..a337a3cd2 100644
--- a/app/models/token.rb
+++ b/app/models/token.rb
@@ -15,8 +15,11 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
+require 'rails_generator/secret_key_generator'
+
 class Token < ActiveRecord::Base
   belongs_to :user
+  validates_uniqueness_of :value
   
   @@validity_time = 1.day
   
@@ -36,9 +39,7 @@ class Token < ActiveRecord::Base
   
 private
   def self.generate_token_value
-    chars = ("a".."z").to_a + ("A".."Z").to_a + ("0".."9").to_a
-    token_value = ''
-    40.times { |i| token_value << chars[rand(chars.size-1)] }
-    token_value
+    s = Rails::SecretKeyGenerator.new(object_id).generate_secret
+    s[0, 40]
   end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 96923900e..f48317610 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -175,8 +175,14 @@ class User < ActiveRecord::Base
   end
   
   def self.find_by_autologin_key(key)
-    token = Token.find_by_action_and_value('autologin', key)
-    token && (token.created_on > Setting.autologin.to_i.day.ago) && token.user.active? ? token.user : nil
+    tokens = Token.find_all_by_action_and_value('autologin', key)
+    # Make sure there's only 1 token that matches the key
+    if tokens.size == 1
+      token = tokens.first
+      if (token.created_on > Setting.autologin.to_i.day.ago) && token.user && token.user.active?
+        token.user
+      end
+    end
   end
   
   # Makes find_by_mail case-insensitive
diff --git a/doc/CHANGELOG b/doc/CHANGELOG
index 6528e756b..07835b78e 100644
--- a/doc/CHANGELOG
+++ b/doc/CHANGELOG
@@ -18,6 +18,7 @@ http://www.redmine.org/
 * Fixed: issues/show should accept user's rss key
 * Fixed: consistency of custom fields display on the issue detail view
 * Fixed: wiki comments length validation is missing
+* Fixed: weak autologin token generation algorithm causes duplicate tokens
 
 
 == 2009-04-05 v0.8.3