diff --git a/lib/factory_girl.rb b/lib/factory_girl.rb
index b8ce7b6..be1aae8 100644
--- a/lib/factory_girl.rb
+++ b/lib/factory_girl.rb
@@ -44,7 +44,7 @@ module FactoryGirl
   class DuplicateDefinitionError < RuntimeError; end
 
   def self.factories
-    @factories ||= Registry.new
+    @factories ||= Registry.new("Factory")
   end
 
   def self.register_factory(factory)
@@ -56,7 +56,7 @@ module FactoryGirl
   end
 
   def self.sequences
-    @sequences ||= Registry.new
+    @sequences ||= Registry.new("Sequence")
   end
 
   def self.register_sequence(sequence)
@@ -68,7 +68,7 @@ module FactoryGirl
   end
 
   def self.traits
-    @traits ||= Registry.new
+    @traits ||= Registry.new("Trait")
   end
 
   def self.register_trait(trait)
diff --git a/lib/factory_girl/registry.rb b/lib/factory_girl/registry.rb
index 54be0f2..c8deb22 100644
--- a/lib/factory_girl/registry.rb
+++ b/lib/factory_girl/registry.rb
@@ -2,7 +2,8 @@ module FactoryGirl
   class Registry
     include Enumerable
 
-    def initialize
+    def initialize(name)
+      @name  = name
       @items = {}
     end
 
@@ -12,7 +13,7 @@ module FactoryGirl
     end
 
     def find(name)
-      @items[name.to_sym] or raise ArgumentError.new("Not registered: #{name.to_s}")
+      @items[name.to_sym] or raise ArgumentError.new("#{@name} not registered: #{name.to_s}")
     end
 
     def each(&block)
@@ -35,7 +36,7 @@ module FactoryGirl
 
     def add_as(name, item)
       if registered?(name)
-        raise DuplicateDefinitionError, "Already defined: #{name}"
+        raise DuplicateDefinitionError, "#{@name} already registered: #{name}"
       else
         @items[name.to_sym] = item
       end
diff --git a/spec/acceptance/modify_factories_spec.rb b/spec/acceptance/modify_factories_spec.rb
index 8eb912a..8472422 100644
--- a/spec/acceptance/modify_factories_spec.rb
+++ b/spec/acceptance/modify_factories_spec.rb
@@ -39,7 +39,7 @@ describe "modifying factories" do
     it "doesn't allow the factory to be subsequently defined" do
       expect do
         FactoryGirl.define { factory :user }
-      end.to raise_error(FactoryGirl::DuplicateDefinitionError)
+      end.to raise_error(FactoryGirl::DuplicateDefinitionError, "Factory already registered: user")
     end
 
     it "does allow the factory to be subsequently modified" do
diff --git a/spec/acceptance/traits_spec.rb b/spec/acceptance/traits_spec.rb
index 94621f2..5c5950e 100644
--- a/spec/acceptance/traits_spec.rb
+++ b/spec/acceptance/traits_spec.rb
@@ -165,6 +165,6 @@ describe "an instance generated by a factory with multiple traits" do
 
   context "factory outside of scope" do
     subject     { FactoryGirl.create(:user_without_admin_scoping) }
-    it { expect { subject }.to raise_error(ArgumentError, "Not registered: admin_trait") }
+    it { expect { subject }.to raise_error(ArgumentError, "Trait not registered: admin_trait") }
   end
 end
diff --git a/spec/factory_girl/registry_spec.rb b/spec/factory_girl/registry_spec.rb
index 83fbbcd..805f85c 100644
--- a/spec/factory_girl/registry_spec.rb
+++ b/spec/factory_girl/registry_spec.rb
@@ -6,8 +6,9 @@ describe FactoryGirl::Registry do
   let(:factory)              { FactoryGirl::Factory.new(:object) }
   let(:other_factory)        { FactoryGirl::Factory.new(:string) }
   let(:factory_with_aliases) { FactoryGirl::Factory.new(:string, :aliases => aliases) }
+  let(:registry_name)        { "Factory" }
 
-  subject { FactoryGirl::Registry.new }
+  subject { FactoryGirl::Registry.new(registry_name) }
 
   it { should be_kind_of(Enumerable) }
 
@@ -17,7 +18,7 @@ describe FactoryGirl::Registry do
   end
 
   it "raises when finding an unregistered factory" do
-    expect { subject.find(:bogus) }.to raise_error(ArgumentError)
+    expect { subject.find(:bogus) }.to raise_error(ArgumentError, "Factory not registered: bogus")
   end
 
   it "adds and returns a factory" do
@@ -62,7 +63,7 @@ describe FactoryGirl::Registry do
 
   it "doesn't allow a duplicate name" do
     expect { 2.times { subject.add(factory) } }.
-      to raise_error(FactoryGirl::DuplicateDefinitionError)
+      to raise_error(FactoryGirl::DuplicateDefinitionError, "Factory already registered: object")
   end
 
   it "registers aliases" do