diff --git a/middleman-core/middleman-core.gemspec b/middleman-core/middleman-core.gemspec
index d9ef7045..8d4af8ad 100644
--- a/middleman-core/middleman-core.gemspec
+++ b/middleman-core/middleman-core.gemspec
@@ -16,21 +16,22 @@ Gem::Specification.new do |s|
   s.test_files   = `git ls-files -z -- {fixtures,features}/*`.split("\0")
   s.executable   = "middleman"
   s.require_path = "lib"
-  
+  s.required_ruby_version = '>= 1.9.3'
+
   # Core
   s.add_dependency("bundler", ["~> 1.1"])
   s.add_dependency("rack", [">= 1.4.5"])
   s.add_dependency("tilt", ["~> 1.3.6"])
-  
+
   # Builder
   s.add_dependency("rack-test", ["~> 0.6.1"])
-  
+
   # CLI
   s.add_dependency("thor", [">= 0.15.2", "< 2.0"])
-  
+
   # Helpers
   s.add_dependency("activesupport", ["~> 3.2.6"])
-  
+
   # Watcher
   s.add_dependency("listen", ["~> 1.1"])
 
diff --git a/middleman/middleman.gemspec b/middleman/middleman.gemspec
index bf4c2948..0c44da8a 100644
--- a/middleman/middleman.gemspec
+++ b/middleman/middleman.gemspec
@@ -16,6 +16,7 @@ Gem::Specification.new do |s|
   s.files         = `git ls-files -z`.split("\0")
   s.test_files    = `git ls-files -z -- {fixtures,features}/*`.split("\0")
   s.require_paths = ["lib"]
+  s.required_ruby_version = '>= 1.9.3'
 
   s.add_dependency("middleman-core", Middleman::VERSION)
   s.add_dependency("middleman-sprockets", ">= 3.1.2")