diff --git a/lib/factory_girl/syntax/default.rb b/lib/factory_girl/syntax/default.rb
index b952cdc..2f9aa69 100644
--- a/lib/factory_girl/syntax/default.rb
+++ b/lib/factory_girl/syntax/default.rb
@@ -15,7 +15,7 @@ module FactoryGirl
         def factory(name, options = {}, &block)
           factory = Factory.new(name, options)
           proxy = FactoryGirl::DefinitionProxy.new(factory)
-          proxy.instance_eval(&block)
+          proxy.instance_eval(&block) if block_given?
           if parent = options.delete(:parent)
             factory.inherit_from(FactoryGirl.factory_by_name(parent))
           end
diff --git a/spec/acceptance/attribute_aliases_spec.rb b/spec/acceptance/attribute_aliases_spec.rb
index 0e150cf..2d2c756 100644
--- a/spec/acceptance/attribute_aliases_spec.rb
+++ b/spec/acceptance/attribute_aliases_spec.rb
@@ -10,8 +10,7 @@ describe "attribute aliases" do
     end
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :post do
         user
diff --git a/spec/acceptance/attributes_for_spec.rb b/spec/acceptance/attributes_for_spec.rb
index d8cda1c..8d2138c 100644
--- a/spec/acceptance/attributes_for_spec.rb
+++ b/spec/acceptance/attributes_for_spec.rb
@@ -15,8 +15,7 @@ describe "a generated attributes hash" do
     end
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :post do
         title { "default title" }
diff --git a/spec/acceptance/build_spec.rb b/spec/acceptance/build_spec.rb
index 2194191..da50a69 100644
--- a/spec/acceptance/build_spec.rb
+++ b/spec/acceptance/build_spec.rb
@@ -12,8 +12,7 @@ describe "a built instance" do
     end
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :post do
         user
diff --git a/spec/acceptance/build_stubbed_spec.rb b/spec/acceptance/build_stubbed_spec.rb
index ce0406d..60c86c5 100644
--- a/spec/acceptance/build_stubbed_spec.rb
+++ b/spec/acceptance/build_stubbed_spec.rb
@@ -14,8 +14,7 @@ describe "a generated stub instance" do
     end
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :post do
         title { "default title" }
diff --git a/spec/acceptance/create_spec.rb b/spec/acceptance/create_spec.rb
index 624df73..92a88ca 100644
--- a/spec/acceptance/create_spec.rb
+++ b/spec/acceptance/create_spec.rb
@@ -12,8 +12,7 @@ describe "a created instance" do
     end
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :post do
         user
diff --git a/spec/acceptance/default_strategy_spec.rb b/spec/acceptance/default_strategy_spec.rb
index 9127701..e06dc77 100644
--- a/spec/acceptance/default_strategy_spec.rb
+++ b/spec/acceptance/default_strategy_spec.rb
@@ -6,8 +6,7 @@ describe "default strategy" do
     define_model('User')
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
     end
 
     Factory(:user).should_not be_new_record
@@ -17,8 +16,7 @@ describe "default strategy" do
     define_model('User')
 
     FactoryGirl.define do
-      factory :user, :default_strategy => :build do
-      end
+      factory :user, :default_strategy => :build
     end
 
     Factory(:user).should be_new_record
diff --git a/spec/acceptance/definition_spec.rb b/spec/acceptance/definition_spec.rb
index 21276c0..0f4ce51 100644
--- a/spec/acceptance/definition_spec.rb
+++ b/spec/acceptance/definition_spec.rb
@@ -6,8 +6,7 @@ describe "an instance generated by a factory with a custom class name" do
     define_model("User", :admin => :boolean)
 
     FactoryGirl.define do
-      factory :user do
-      end
+      factory :user
 
       factory :admin, :class => User do
         admin { true }
diff --git a/spec/acceptance/definition_without_block_spec.rb b/spec/acceptance/definition_without_block_spec.rb
new file mode 100644
index 0000000..e37b0cb
--- /dev/null
+++ b/spec/acceptance/definition_without_block_spec.rb
@@ -0,0 +1,16 @@
+require 'spec_helper'
+require 'acceptance/acceptance_helper'
+
+describe "an instance generated by a factory" do
+  before do
+    define_model("User")
+
+    FactoryGirl.define do
+      factory :user
+    end
+  end
+
+  it "registers the user factory" do
+    FactoryGirl.factory_by_name(:user).should be_a(FactoryGirl::Factory)
+  end
+end