diff --git a/lib/rack/cors.rb b/lib/rack/cors.rb
index 2d81b40..cdad5b2 100644
--- a/lib/rack/cors.rb
+++ b/lib/rack/cors.rb
@@ -10,6 +10,8 @@ class Cors
     VARY_HEADER_KEY       = 'Vary'.freeze
     DEFAULT_VARY_HEADERS  = ['Origin'].freeze
 
+    RACK_LOGGER = 'rack.logger'.freeze
+
     def initialize(app, opts={}, &block)
       @app = app
       @debug_mode = !!opts[:debug]
@@ -125,8 +127,8 @@ def select_logger(env)
         elsif defined?(Rails) && Rails.logger
           Rails.logger
 
-        elsif env['rack.logger']
-          env['rack.logger']
+        elsif env[RACK_LOGGER]
+          env[RACK_LOGGER]
 
         else
           ::Logger.new(STDOUT).tap { |logger| logger.level = ::Logger::Severity::DEBUG }
@@ -248,6 +250,9 @@ def append_header(headers)
       end
 
       class Resources
+
+        attr_reader :resources
+
         def initialize
           @origins = []
           @resources = []
@@ -311,7 +316,7 @@ def initialize(public_resource, path, opts={})
           raise CorsMisconfigurationError if public_resource && opts[:credentials]
 
           self.path         = path
-          self.credentials  = opts[:credentials].nil? ? !public_resource : opts[:credentials]
+          self.credentials  = public_resource ? false : (opts[:credentials] == true)
           self.max_age      = opts[:max_age] || 1728000
           self.pattern      = compile(path)
           self.if_proc      = opts[:if]
diff --git a/test/unit/dsl_test.rb b/test/unit/dsl_test.rb
index cd5c07b..074d754 100644
--- a/test/unit/dsl_test.rb
+++ b/test/unit/dsl_test.rb
@@ -55,4 +55,15 @@
 
     resources.first.allow_origin?('file://').must_equal true
   end
+
+  it 'should default credentials option to false' do
+    cors = Rack::Cors.new(Proc.new {}) do
+      allow do
+        origins 'example.net'
+        resource '/', :headers => :any
+      end
+    end
+    resources = cors.send :all_resources
+    resources.first.resources.first.credentials.must_equal false
+  end
 end