diff --git a/ruby/google-protobuf.gemspec b/ruby/google-protobuf.gemspec
index 67b15c3323f8..2f7ca3c41e56 100644
--- a/ruby/google-protobuf.gemspec
+++ b/ruby/google-protobuf.gemspec
@@ -10,6 +10,7 @@ Gem::Specification.new do |s|
   s.require_paths = ["lib"]
   s.files       = Dir.glob('lib/**/*.rb')
   if RUBY_PLATFORM == "java"
+    s.platform  = "java"
     s.files     += ["lib/google/protobuf_java.jar"]
   else
     s.files     += Dir.glob('ext/**/*')