diff --git a/lib/red_storm/environment.rb b/lib/red_storm/environment.rb
index 5f40733..d064687 100644
--- a/lib/red_storm/environment.rb
+++ b/lib/red_storm/environment.rb
@@ -22,7 +22,12 @@ module RedStorm
     $1
   end
 
-  module_function :current_ruby_mode
+  def jruby_mode_token(ruby_version = nil)
+    version_map = {"1.8" => "RUBY1_8", "--1.8" => "RUBY1_8", "1.9" => "RUBY1_9", "--1.9" => "RUBY1_9"}
+    version_map[ruby_version.to_s] || version_map[RedStorm.current_ruby_mode]
+  end
+
+  module_function :current_ruby_mode, :jruby_mode_token
 
   # puts("*** LAUNCH_PATH=#{LAUNCH_PATH}")
   # puts("*** JAR_CONTEXT=#{JAR_CONTEXT}")
diff --git a/lib/tasks/red_storm.rake b/lib/tasks/red_storm.rake
index fcd825c..de34fec 100644
--- a/lib/tasks/red_storm.rake
+++ b/lib/tasks/red_storm.rake
@@ -29,8 +29,7 @@ end
 
 task :launch, :env, :ruby_mode, :class_file do |t, args|
   # use ruby mode parameter or default to current interpreter version
-  version_map = {"--1.8" => "RUBY1_8", "--1.9" => "RUBY1_9"}
-  version_token = version_map[args[:ruby_mode] || "--#{RedStorm.current_ruby_mode}"]
+  version_token = RedStorm.jruby_mode_token(args[:ruby_mode])
   
   command = case args[:env]
   when "local"
diff --git a/spec/red_storm/environment_spec.rb b/spec/red_storm/environment_spec.rb
new file mode 100644
index 0000000..ca6c625
--- /dev/null
+++ b/spec/red_storm/environment_spec.rb
@@ -0,0 +1,31 @@
+require 'spec_helper'
+require 'red_storm/environment'
+
+describe RedStorm do
+
+  describe "jruby_mode_token" do
+
+    it "should default to current JRuby mode" do
+      RedStorm.should_receive(:current_ruby_mode).and_return("1.8")
+      RedStorm.jruby_mode_token.should == "RUBY1_8"
+
+      RedStorm.should_receive(:current_ruby_mode).and_return("1.9")
+      RedStorm.jruby_mode_token.should == "RUBY1_9"
+    end
+
+    it "should use provided version" do
+      RedStorm.should_receive(:current_ruby_mode).never
+
+      RedStorm.jruby_mode_token("1.8").should == "RUBY1_8"
+      RedStorm.jruby_mode_token("--1.8").should == "RUBY1_8"
+
+      RedStorm.jruby_mode_token("1.9").should == "RUBY1_9"
+      RedStorm.jruby_mode_token("--1.9").should == "RUBY1_9"
+    end
+
+    it "should default to current JRuby mode on invalid version" do
+      RedStorm.should_receive(:current_ruby_mode).and_return("1.9")
+      RedStorm.jruby_mode_token("foobar").should == "RUBY1_9"
+    end
+  end
+end