diff --git a/CHANGELOG.rdoc b/CHANGELOG.rdoc
index 0843027..af4c6a9 100644
--- a/CHANGELOG.rdoc
+++ b/CHANGELOG.rdoc
@@ -1,3 +1,5 @@
+* Adding clear_aliased_actions to Ability which removes previously defined actions including defaults - see issue #20
+
 * Append aliased actions (don't overwrite them) - see issue #20
 
 * Adding custom message argument to unauthorized! method (thanks tjwallace) - see issue #18
diff --git a/lib/cancan/ability.rb b/lib/cancan/ability.rb
index 1fab685..702075e 100644
--- a/lib/cancan/ability.rb
+++ b/lib/cancan/ability.rb
@@ -160,12 +160,18 @@ module CanCan
       aliased_actions[target] += args
     end
     
-    private
-    
+    # Returns a hash of aliased actions. The key is the target and the value is an array of actions aliasing the key.
     def aliased_actions
       @aliased_actions ||= default_alias_actions
     end
     
+    # Removes previously aliased actions including the defaults.
+    def clear_aliased_actions
+      @aliased_actions = {}
+    end
+    
+    private
+    
     def default_alias_actions
       {
         :read => [:index, :show],
diff --git a/spec/cancan/ability_spec.rb b/spec/cancan/ability_spec.rb
index e6178a1..20bc1a9 100644
--- a/spec/cancan/ability_spec.rb
+++ b/spec/cancan/ability_spec.rb
@@ -49,9 +49,7 @@ describe CanCan::Ability do
   
   it "should alias update or destroy actions to modify action" do
     @ability.alias_action :update, :destroy, :to => :modify
-    @ability.can :modify, :all do |object_class, object|
-      :modify_called
-    end
+    @ability.can(:modify, :all) { :modify_called }
     @ability.can?(:update, 123).should == :modify_called
     @ability.can?(:destroy, 123).should == :modify_called
   end
@@ -126,10 +124,12 @@ describe CanCan::Ability do
   it "should append aliased actions" do
     @ability.alias_action :update, :to => :modify
     @ability.alias_action :destroy, :to => :modify
-    @ability.can :modify, :all do |object_class, object|
-      :modify_called
-    end
-    @ability.can?(:update, 123).should == :modify_called
-    @ability.can?(:destroy, 123).should == :modify_called
+    @ability.aliased_actions[:modify].should == [:update, :destroy]
+  end
+  
+  it "should clear aliased actions" do
+    @ability.alias_action :update, :to => :modify
+    @ability.clear_aliased_actions
+    @ability.aliased_actions[:modify].should be_nil
   end
 end