1 files changed, 10 insertions, 1 deletions
diff --git a/lib/rubygems/rdoc.rb b/lib/rubygems/rdoc.rb
index 907dcd9431..977a51da01 100644
--- a/lib/rubygems/rdoc.rb
+++ b/lib/rubygems/rdoc.rb
@@ -6,8 +6,17 @@ begin
   require "rdoc/rubygems_hook"
   module Gem
     RDoc = ::RDoc::RubygemsHook
+
+    ##
+    # Returns whether RDoc defines its own install hooks through a RubyGems
+    # plugin. This and whatever is guarded by it can be removed once no
+    # supported Ruby ships with RDoc older than 6.9.0.
+
+    def self.rdoc_hooks_defined_via_plugin?
+      Gem::Version.new(::RDoc::VERSION) >= Gem::Version.new("6.9.0")
+    end
   end
 
-  Gem.done_installing(&Gem::RDoc.method(:generation_hook))
+  Gem.done_installing(&Gem::RDoc.method(:generation_hook)) unless Gem.rdoc_hooks_defined_via_plugin?
 rescue LoadError
 end