diff --git a/Gemfile.lock b/Gemfile.lock
index 044ee41..d0b5933 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -7,9 +7,9 @@ PATH
       haml (~> 3.1)
       mail (~> 2.3)
       sinatra (~> 1.2)
-      skinny
+      skinny (~> 0.2.2)
       sqlite3 (~> 1.3)
-      thin
+      thin (~> 1.4.1)
 
 GEM
   remote: http://rubygems.org/
diff --git a/mailcatcher.gemspec b/mailcatcher.gemspec
index e873e01..df0c838 100644
--- a/mailcatcher.gemspec
+++ b/mailcatcher.gemspec
@@ -38,8 +38,8 @@ Gem::Specification.new do |s|
   s.add_dependency "mail", "~> 2.3"
   s.add_dependency "sinatra", "~> 1.2"
   s.add_dependency "sqlite3", "~> 1.3"
-  s.add_dependency "thin"
-  s.add_dependency "skinny"
+  s.add_dependency "thin", "~> 1.4.1"
+  s.add_dependency "skinny", "~> 0.2.2"
 
   s.add_development_dependency "coffee-script"
   s.add_development_dependency "compass"