diff --git a/history.md b/history.md
index df26956..26edeaf 100644
--- a/history.md
+++ b/history.md
@@ -77,6 +77,9 @@ This release is largely API compatible, but makes several breaking changes.
 - Refactor URI parsing to happen earlier, in Request initialization.
 - When adding URL params, handle URLs that already contain params.
 - Add a few more exception classes for obscure HTTP status codes.
+- Drop ancient backwards compatibility for old Resource initializer.
+  No longer supported: `RestClient::Resource.new(url, username, pass)`
+  Instead use: `RestClient::Resource.new(url, user: username, password: pass)`
 
 # 2.0.0.rc1
 
diff --git a/lib/restclient/resource.rb b/lib/restclient/resource.rb
index 955f682..08940d5 100644
--- a/lib/restclient/resource.rb
+++ b/lib/restclient/resource.rb
@@ -36,14 +36,10 @@ module RestClient
   class Resource
     attr_reader :url, :options, :block
 
-    def initialize(url, options={}, backwards_compatibility=nil, &block)
+    def initialize(url, options={}, &block)
       @url = url
       @block = block
-      if options.class == Hash
-        @options = options
-      else # compatibility with previous versions
-        @options = { :user => options, :password => backwards_compatibility }
-      end
+      @options = options
     end
 
     def get(additional_headers={}, &block)
diff --git a/spec/unit/resource_spec.rb b/spec/unit/resource_spec.rb
index 056a8fb..ea5ec26 100644
--- a/spec/unit/resource_spec.rb
+++ b/spec/unit/resource_spec.rb
@@ -46,10 +46,10 @@ describe RestClient::Resource do
     @resource = RestClient::Resource.new('http://some/resource')
   end
 
-  it "is backwards compatible with previous constructor" do
-    @resource = RestClient::Resource.new('http://some/resource', 'user', 'pass')
-    @resource.user.should eq 'user'
-    @resource.password.should eq 'pass'
+  it "is NOT backwards compatible with previous constructor" do
+    lambda {
+      @resource = RestClient::Resource.new('http://some/resource', 'user', 'pass')
+    }.should raise_error(ArgumentError)
   end
 
   it "concatenates urls, inserting a slash when it needs one" do