diff --git a/Gemfile.lock b/Gemfile.lock
index 13ae2ac..932e48f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -8,13 +8,12 @@ GEM
   remote: http://rubygems.org/
   specs:
     mocha (0.9.9)
-      rake
-    rake (0.8.7)
+    rake (0.9.2.2)
     rcov (0.9.9)
     test-spec (0.10.0)
     test-unit (2.1.2)
     xml-simple (1.0.12)
-    yard (0.6.2)
+    yard (0.8.2.1)
 
 PLATFORMS
   ruby
@@ -22,6 +21,7 @@ PLATFORMS
 DEPENDENCIES
   amazon-ec2!
   mocha (>= 0.9.9)
+  rake (>= 0.8.7)
   rcov (>= 0.9.9)
   test-spec (>= 0.10.0)
   test-unit (>= 2.1.2)
diff --git a/amazon-ec2.gemspec b/amazon-ec2.gemspec
index 835ac37..db25725 100644
--- a/amazon-ec2.gemspec
+++ b/amazon-ec2.gemspec
@@ -26,6 +26,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency('test-unit', '>= 2.1.2')
   s.add_development_dependency('test-spec', '>= 0.10.0')
   s.add_development_dependency('rcov', '>= 0.9.9')
+  s.add_development_dependency('rake', '>= 0.8.7')
 #  s.add_development_dependency('perftools.rb', '>= 0.5.4')
   s.add_development_dependency('yard', '>= 0.6.2')
 
diff --git a/lib/AWS/EC2/instances.rb b/lib/AWS/EC2/instances.rb
index 71f7653..d234a06 100644
--- a/lib/AWS/EC2/instances.rb
+++ b/lib/AWS/EC2/instances.rb
@@ -37,7 +37,7 @@ def run_instances( options = {} )
         raise ArgumentError, ":image_id must be provided" if options[:image_id].nil? || options[:image_id].empty?
         raise ArgumentError, ":min_count is not valid" unless options[:min_count].to_i > 0
         raise ArgumentError, ":max_count is not valid or must be >= :min_count" unless options[:max_count].to_i > 0 && options[:max_count].to_i >= options[:min_count].to_i
-        raise ArgumentError, ":instance_type must specify a valid instance type" unless options[:instance_type].nil? || ["t1.micro", "m1.small", "m1.large", "m1.xlarge", "m2.xlarge", "c1.medium", "c1.xlarge", "m2.2xlarge", "m2.4xlarge", "cc1.4xlarge"].include?(options[:instance_type])
+        raise ArgumentError, ":instance_type must specify a valid instance type" unless options[:instance_type].nil? || ["t1.micro", "m1.small", "m1.medium", "m1.large", "m1.xlarge", "m2.xlarge", "c1.medium", "c1.xlarge", "m2.2xlarge", "m2.4xlarge", "cc1.4xlarge"].include?(options[:instance_type])
         raise ArgumentError, ":monitoring_enabled must be 'true' or 'false'" unless options[:monitoring_enabled].nil? || [true, false].include?(options[:monitoring_enabled])
         raise ArgumentError, ":disable_api_termination must be 'true' or 'false'" unless options[:disable_api_termination].nil? || [true, false].include?(options[:disable_api_termination])
         raise ArgumentError, ":instance_initiated_shutdown_behavior must be 'stop' or 'terminate'" unless options[:instance_initiated_shutdown_behavior].nil? || ["stop", "terminate"].include?(options[:instance_initiated_shutdown_behavior])