diff --git a/lib/flipper/adapter.rb b/lib/flipper/adapter.rb
index 1eb8a82d8..1dbb91592 100644
--- a/lib/flipper/adapter.rb
+++ b/lib/flipper/adapter.rb
@@ -101,7 +101,7 @@ def read(key)
 
     # Public: Set a key to a value.
     def write(key, value)
-      perform_update(:write, key, value)
+      perform_update(:write, key, value.to_s)
     end
 
     # Public: Deletes a key.
@@ -116,12 +116,12 @@ def set_members(key)
 
     # Public: Adds a value to a set.
     def set_add(key, value)
-      perform_update(:set_add, key, value)
+      perform_update(:set_add, key, value.to_s)
     end
 
     # Public: Deletes a value from a set.
     def set_delete(key, value)
-      perform_update(:set_delete, key, value)
+      perform_update(:set_delete, key, value.to_s)
     end
 
     # Public: Determines equality for an adapter instance when compared to
diff --git a/lib/flipper/adapters/memory.rb b/lib/flipper/adapters/memory.rb
index 0f3b133c5..848e3541e 100644
--- a/lib/flipper/adapters/memory.rb
+++ b/lib/flipper/adapters/memory.rb
@@ -15,7 +15,7 @@ def read(key)
 
       # Public
       def write(key, value)
-        @source[key.to_s] = value
+        @source[key.to_s] = value.to_s
       end
 
       # Public
@@ -26,13 +26,13 @@ def delete(key)
       # Public
       def set_add(key, value)
         ensure_set_initialized(key)
-        @source[key.to_s].add(value)
+        @source[key.to_s].add(value.to_s)
       end
 
       # Public
       def set_delete(key, value)
         ensure_set_initialized(key)
-        @source[key.to_s].delete(value)
+        @source[key.to_s].delete(value.to_s)
       end
 
       # Public
diff --git a/lib/flipper/spec/shared_adapter_specs.rb b/lib/flipper/spec/shared_adapter_specs.rb
index 66a5fc9a6..ebe95b0c6 100644
--- a/lib/flipper/spec/shared_adapter_specs.rb
+++ b/lib/flipper/spec/shared_adapter_specs.rb
@@ -82,18 +82,27 @@
     Flipper.new(subject).should_not be_nil
   end
 
-  context "integration spot-checks" do
+  context "working with sets" do
+    it "always returns strings" do
+      subject.set_add key, 1
+      subject.set_add key, 2
+      subject.set_members(key).should eq(Set['1', '2'])
+      subject.set_delete key, 2
+      subject.set_members(key).should eq(Set['1'])
+    end
+  end
 
+  context "integration spot-checks" do
     let(:instance) { Flipper.new(subject) }
     let(:feature) { instance[:feature] }
     let(:actor) { Struct.new(:id).new(1) }
 
-    describe "percentage of actors" do
+    context "percentage of actors" do
       let(:percentage) { instance.actors(10) }
       it_should_behave_like 'a working percentage'
     end
 
-    describe "random percentage" do
+    context "random percentage" do
       let(:percentage) { instance.random(10) }
       it_should_behave_like 'a working percentage'
     end
diff --git a/spec/flipper/adapter_spec.rb b/spec/flipper/adapter_spec.rb
index 5d63a184a..e08da7060 100644
--- a/spec/flipper/adapter_spec.rb
+++ b/spec/flipper/adapter_spec.rb
@@ -5,7 +5,8 @@
 
 describe Flipper::Adapter do
   let(:local_cache)  { {} }
-  let(:adapter)      { Flipper::Adapters::Memory.new }
+  let(:source)       { {} }
+  let(:adapter)      { Flipper::Adapters::Memory.new(source) }
   let(:features_key) { described_class::FeaturesKey }
 
   subject { described_class.new(adapter, :local_cache => local_cache) }
@@ -134,7 +135,7 @@
 
     describe "#set_members" do
       before do
-        adapter.write 'foo', Set['1', '2']
+        source['foo'] = Set['1', '2']
         @result = subject.set_members('foo')
       end
 
@@ -180,7 +181,7 @@
 
     describe "#set_add" do
       before do
-        adapter.write 'foo', Set['1']
+        source['foo'] = Set['1']
         local_cache['foo'] = Set['1']
         subject.set_add 'foo', '2'
       end
@@ -196,7 +197,7 @@
 
     describe "#set_delete" do
       before do
-        adapter.write 'foo', Set['1', '2', '3']
+        source['foo'] = Set['1', '2', '3']
         local_cache['foo'] = Set['1', '2', '3']
         subject.set_delete 'foo', '3'
       end
@@ -233,7 +234,7 @@
 
     describe "#set_members" do
       before do
-        adapter.write 'foo', Set['1', '2']
+        source['foo'] = Set['1', '2']
         @result = subject.set_members('foo')
       end
 
@@ -280,7 +281,7 @@
 
     describe "#set_add" do
       before do
-        adapter.write 'foo', Set['1']
+        source['foo'] = Set['1']
         local_cache['foo'] = Set['1']
         subject.set_add 'foo', '2'
       end
@@ -296,7 +297,7 @@
 
     describe "#set_delete" do
       before do
-        adapter.write 'foo', Set['1', '2', '3']
+        source['foo'] = Set['1', '2', '3']
         local_cache['foo'] = Set['1', '2', '3']
         subject.set_delete 'foo', '3'
       end