diff --git a/lib/redmine/plugin.rb b/lib/redmine/plugin.rb
index 48d04dcac..7e1fa1763 100644
--- a/lib/redmine/plugin.rb
+++ b/lib/redmine/plugin.rb
@@ -275,7 +275,7 @@ module Redmine
 
     def compare_versions(requirement, current)
       requirement = requirement.split('.').collect(&:to_i)
-      requirement <=> current.slice(0, requirement.size)
+      requirement <=> current.slice(0, requirement.size).collect(&:to_i)
     end
     private :compare_versions
 
diff --git a/test/unit/lib/redmine/plugin_test.rb b/test/unit/lib/redmine/plugin_test.rb
index 92898e181..0672d9d55 100644
--- a/test/unit/lib/redmine/plugin_test.rb
+++ b/test/unit/lib/redmine/plugin_test.rb
@@ -134,6 +134,8 @@ class Redmine::PluginTest < ActiveSupport::TestCase
     assert_raise Redmine::PluginRequirementError do
       plugin.requires_redmine(:version => '2.2')
     end
+    assert plugin.requires_redmine(:version => '2.1.3.stable')
+    assert plugin.requires_redmine(:version => '2.1.3.devel')
     # Version range
     assert plugin.requires_redmine(:version => '2.0.0'..'2.2.4')
     assert plugin.requires_redmine(:version => '2.1.3'..'2.2.4')