diff --git a/lib/rubygems/basic_specification.rb b/lib/rubygems/basic_specification.rb
index 816fc8cb8f..0e65f26d10 100644
--- a/lib/rubygems/basic_specification.rb
+++ b/lib/rubygems/basic_specification.rb
@@ -78,7 +78,7 @@ class Gem::BasicSpecification
     elsif missing_extensions?
       @ignored = true
 
-      if RUBY_ENGINE == platform || Gem::Platform.local === platform
+      if Gem::Platform::RUBY == platform || Gem::Platform.local === platform
         warn "Ignoring #{full_name} because its extensions are not built. " +
           "Try: gem pristine #{name} --version #{version}"
       end