diff --git a/Changes.md b/Changes.md
index db2bf616..7a28b626 100644
--- a/Changes.md
+++ b/Changes.md
@@ -1,3 +1,9 @@
+2.17.8
+-----------
+
+- Tighten allowed gem versions to prevent future incompatibility.  Fixes
+  breakage with Celluloid 0.16.
+
 2.17.7
 -----------
 
diff --git a/lib/sidekiq/version.rb b/lib/sidekiq/version.rb
index dca173d8..f9e45b90 100644
--- a/lib/sidekiq/version.rb
+++ b/lib/sidekiq/version.rb
@@ -1,3 +1,3 @@
 module Sidekiq
-  VERSION = "2.17.7"
+  VERSION = "2.17.8"
 end
diff --git a/sidekiq.gemspec b/sidekiq.gemspec
index 595df181..ddcb8137 100644
--- a/sidekiq.gemspec
+++ b/sidekiq.gemspec
@@ -14,14 +14,14 @@ Gem::Specification.new do |gem|
   gem.name          = "sidekiq"
   gem.require_paths = ["lib"]
   gem.version       = Sidekiq::VERSION
-  gem.add_dependency                  'redis', '>= 3.0.6'
-  gem.add_dependency                  'redis-namespace', '>= 1.3.1'
-  gem.add_dependency                  'connection_pool', '>= 1.0.0'
-  gem.add_dependency                  'celluloid', '>= 0.15.2'
+  gem.add_dependency                  'redis', '~> 3.1'
+  gem.add_dependency                  'redis-namespace', '~> 1.3'
+  gem.add_dependency                  'connection_pool', '~> 2.0'
+  gem.add_dependency                  'celluloid', '0.15.2'
   gem.add_dependency                  'json'
   gem.add_development_dependency      'sinatra'
   gem.add_development_dependency      'minitest', '~> 4.2'
   gem.add_development_dependency      'rake'
-  gem.add_development_dependency      'rails', '>= 4.0.0'
+  gem.add_development_dependency      'rails', '4.0.5'
   gem.add_development_dependency      'coveralls'
 end