diff --git a/lib/split/user.rb b/lib/split/user.rb
index 02a26653..7d506a87 100644
--- a/lib/split/user.rb
+++ b/lib/split/user.rb
@@ -4,8 +4,8 @@ class User
     def_delegators :@user, :keys, :[], :[]=, :delete
     attr_reader :user
 
-    def initialize(context)
-      @user = Split::Persistence.adapter.new(context)
+    def initialize(context, adapter=nil)
+      @user = adapter || Split::Persistence.adapter.new(context)
     end
 
     def cleanup_old_experiments!
diff --git a/spec/user_spec.rb b/spec/user_spec.rb
index b76674df..3a11bc27 100644
--- a/spec/user_spec.rb
+++ b/spec/user_spec.rb
@@ -60,4 +60,17 @@
       end
     end
   end
+
+  context "instantiated with custom adapter" do
+    let(:custom_adapter) { double(:persistence_adapter) }
+
+    before do
+      @subject = described_class.new(context, custom_adapter)
+    end
+
+    it "sets user to the custom adapter" do
+      expect(@subject.user).to eq(custom_adapter)
+    end
+  end
+
 end