diff --git a/lib/workless/scaler.rb b/lib/workless/scaler.rb
index 90621df..3ea6302 100644
--- a/lib/workless/scaler.rb
+++ b/lib/workless/scaler.rb
@@ -11,9 +11,9 @@ def self.included(base)
         base.send :extend, ClassMethods
         if base.to_s =~ /ActiveRecord/
           base.class_eval do
-            after_commit "self.class.scaler.down", :on => :update, :if => Proc.new {|r| !r.failed_at.nil? }
-            after_commit "self.class.scaler.down", :on => :destroy, :if => Proc.new {|r| r.destroyed? or !r.failed_at.nil? }
-            after_commit "self.class.scaler.up", :on => :create
+            after_commit -> { self.class.scaler.down }, :on => :update, :if => Proc.new {|r| !r.failed_at.nil? }
+            after_commit -> { self.class.scaler.down }, :on => :destroy, :if => Proc.new {|r| r.destroyed? or !r.failed_at.nil? }
+            after_commit -> { self.class.scaler.up }, :on => :create
           end          
         elsif base.to_s =~ /Sequel/
           base.send(:define_method, 'after_destroy') do
diff --git a/workless.gemspec b/workless.gemspec
index 4ee4180..438593b 100644
--- a/workless.gemspec
+++ b/workless.gemspec
@@ -24,6 +24,6 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency(%q<rush>)
   s.add_runtime_dependency(%q<delayed_job>, [">= 2.0.7"])
 
-  s.add_development_dependency(%q<rspec>)
+  s.add_development_dependency(%q<rspec>, ["~> 2.0"])
 end