diff --git a/app/models/repository/mercurial.rb b/app/models/repository/mercurial.rb
index c38236fc8..102c6dda8 100644
--- a/app/models/repository/mercurial.rb
+++ b/app/models/repository/mercurial.rb
@@ -71,6 +71,7 @@ class Repository::Mercurial < Repository
 
   # Finds and returns a revision with a number or the beginning of a hash
   def find_changeset_by_name(name)
+    return nil if name.nil? || name.empty?
     if /[^\d]/ =~ name or name.to_s.size > 8
       e = changesets.find(:first, :conditions => ['scmid = ?', name.to_s])
     else
diff --git a/test/functional/repositories_mercurial_controller_test.rb b/test/functional/repositories_mercurial_controller_test.rb
index 1afe42571..b565863c3 100644
--- a/test/functional/repositories_mercurial_controller_test.rb
+++ b/test/functional/repositories_mercurial_controller_test.rb
@@ -195,6 +195,16 @@ class RepositoriesMercurialControllerTest < ActionController::TestCase
                  :attributes => { :class => 'line-num' },
                  :sibling => { :tag => 'td', :content => /watcher =/ }
     end
+
+    def test_empty_revision
+      @repository.fetch_changesets
+      @repository.reload
+      ['', ' ', nil].each do |r|
+        get :revision, :id => 1, :rev => r
+        assert_response 500
+        assert_error_tag :content => /was not found/
+      end
+    end
   else
     puts "Mercurial test repository NOT FOUND. Skipping functional tests !!!"
     def test_fake; assert true end
diff --git a/test/unit/repository_mercurial_test.rb b/test/unit/repository_mercurial_test.rb
index 8921acb76..7523cfe9d 100644
--- a/test/unit/repository_mercurial_test.rb
+++ b/test/unit/repository_mercurial_test.rb
@@ -154,6 +154,14 @@ class RepositoryMercurialTest < ActiveSupport::TestCase
       assert_equal '2:400bb8672109', c.format_identifier
     end
 
+    def test_find_changeset_by_empty_name
+      @repository.fetch_changesets
+      @repository.reload
+      ['', ' ', nil].each do |r|
+        assert_nil @repository.find_changeset_by_name(r)
+      end
+    end
+
     def test_activities
       c = Changeset.new(:repository   => @repository,
                         :committed_on => Time.now,