diff --git a/middleman.gemspec b/middleman.gemspec
index 32e72f76..1453eb8f 100644
--- a/middleman.gemspec
+++ b/middleman.gemspec
@@ -38,7 +38,6 @@ Gem::Specification.new do |s|
 eos
 
   s.add_dependency("rack", ["~> 1.3.0"])
-  # s.add_dependency("eventmachine", ["1.0.0.beta.3"])
   s.add_dependency("thin", ["~> 1.2.11"])
   s.add_dependency("thor", ["~> 0.14.0"])
   s.add_dependency("tilt", ["~> 1.3.1"])
@@ -57,6 +56,7 @@ eos
   
   case Config::CONFIG['host_os'].downcase
   when %r{mswin|mingw}
+    s.add_dependency("eventmachine", ["1.0.0.beta.3"])
     # s.add_runtime_dependency "windows-api", "= 0.4.0"
     # s.add_runtime_dependency "windows-pr", "= 1.1.2"
     s.add_dependency("win32-process", ["~> 0.6.5"])