diff --git a/fake_sqs.gemspec b/fake_sqs.gemspec
index d6188d9..e32a8a6 100644
--- a/fake_sqs.gemspec
+++ b/fake_sqs.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
   gem.license       = "MIT"
 
-  gem.add_dependency "sinatra"
+  gem.add_dependency "sinatra", "~> 1"
   gem.add_dependency "builder"
 
   gem.add_development_dependency "rspec"
@@ -27,6 +27,6 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "faraday"
   gem.add_development_dependency "thin"
   gem.add_development_dependency "verbose_hash_fetch"
-  gem.add_development_dependency "activesupport"
+  gem.add_development_dependency "activesupport", "< 5"
 
 end
diff --git a/lib/fake_sqs/actions/receive_message.rb b/lib/fake_sqs/actions/receive_message.rb
index 55d3e55..b479e3c 100644
--- a/lib/fake_sqs/actions/receive_message.rb
+++ b/lib/fake_sqs/actions/receive_message.rb
@@ -11,13 +11,30 @@ def initialize(options = {})
       def call(name, params)
         queue = @queues.get(name)
         messages = queue.receive_message(params)
+        filtered_message_attribute_names = []
+        params.select{|k,v | k =~ /MessageAttributeName\.\d+/}.each do |key, value|
+          filtered_message_attribute_names << value
+        end
         @responder.call :ReceiveMessage do |xml|
           messages.each do |receipt, message|
             xml.Message do
               xml.MessageId message.id
               xml.ReceiptHandle receipt
               xml.MD5OfBody message.md5
+              xml.MD5OfMessageAttributes message.message_attributes_md5
               xml.Body message.body
+              message.message_attributes.each do |attribute|
+                if filtered_message_attribute_names.include?("All") || filtered_message_attribute_names.include?(attribute)
+                  xml.MessageAttribute do
+                    xml.Name attribute["Name"]
+                    xml.Value do
+                      xml.StringValue attribute["Value.StringValue"] if attribute["Value.StringValue"]
+                      xml.BinaryValue attribute["Value.BinaryValue"] if attribute["Value.BinaryValue"]
+                      xml.DataType attribute["Value.DataType"]
+                    end
+                  end
+                end
+              end
             end
           end
         end
diff --git a/lib/fake_sqs/actions/send_message.rb b/lib/fake_sqs/actions/send_message.rb
index 79adcd1..26440b8 100644
--- a/lib/fake_sqs/actions/send_message.rb
+++ b/lib/fake_sqs/actions/send_message.rb
@@ -13,6 +13,7 @@ def call(name, params)
         message = queue.send_message(params)
         @responder.call :SendMessage do |xml|
           xml.MD5OfMessageBody message.md5
+          xml.MD5OfMessageAttributes message.message_attributes_md5
           xml.MessageId message.id
         end
       end
diff --git a/lib/fake_sqs/message.rb b/lib/fake_sqs/message.rb
index 225147c..7e4c0df 100644
--- a/lib/fake_sqs/message.rb
+++ b/lib/fake_sqs/message.rb
@@ -3,13 +3,14 @@
 module FakeSQS
   class Message
 
-    attr_reader :body, :id, :md5
+    attr_reader :body, :id, :md5, :message_attributes
     attr_accessor :visibility_timeout
 
     def initialize(options = {})
       @body = options.fetch("MessageBody")
       @id = options.fetch("Id") { SecureRandom.uuid }
       @md5 = options.fetch("MD5") { Digest::MD5.hexdigest(@body) }
+      @message_attributes = extract_attributes(options)
     end
 
     def expire!
@@ -32,5 +33,48 @@ def attributes
       }
     end
 
+    def message_attributes_md5
+      sorted_attributes = @message_attributes.sort { |a,b| a["Name"] <=> b["Name"] }
+
+      buffer = sorted_attributes.each_with_object([]) do |attribute, buffer|
+        add_string_to_buffer(attribute["Name"], buffer)
+        add_string_to_buffer(attribute["Value.DataType"], buffer)
+
+        if (attribute["Value.StringValue"])
+          buffer << 1
+          add_string_to_buffer(attribute["Value.StringValue"], buffer)
+        elsif (attribute["Value.BinaryValue"])
+          buffer << 2
+          add_binary_to_buffer(attribute["Value.BinaryValue"], buffer)
+        end
+      end
+      Digest::MD5.hexdigest(buffer.pack("C*"))
+    end
+
+    def add_string_to_buffer(string, buffer)
+      string_bytes = string.force_encoding('UTF-8').bytes.to_a
+      buffer.concat [string_bytes.size].pack("N").bytes.to_a
+      buffer.concat string_bytes
+    end
+
+    def add_binary_to_buffer(binary, buffer)
+      binary_bytes = binary.unpack("m*")[0].bytes.to_a
+      buffer.concat [binary_bytes.size].pack("N").bytes.to_a
+      buffer.concat binary_bytes
+    end
+
+    private
+    def extract_attributes(options)
+      attributes = []
+      options.each {|key, value|
+        if /MessageAttribute\.(?<attr_index>\d+)\.(?<attr_name>.*)/ =~ key
+          index = attr_index.to_i - 1
+          attributes[index] = Hash.new unless attributes[index]
+          attributes[index][attr_name] = value
+        end
+      }
+      attributes
+    end
+
   end
 end
diff --git a/spec/acceptance/message_actions_spec.rb b/spec/acceptance/message_actions_spec.rb
index 8008023..9f2f11b 100644
--- a/spec/acceptance/message_actions_spec.rb
+++ b/spec/acceptance/message_actions_spec.rb
@@ -26,6 +26,24 @@
     expect(result.message_id.size).to eq 36
   end
 
+  specify "SendMessage with message_attributes" do
+    sent_message = sqs.send_message(queue_url: queue_url, message_body: "this is my message", 
+      message_attributes: {"foo_class"=> {string_value: "FooWorker", data_type: "String"}})
+
+    received_message = sqs.receive_message(queue_url: queue_url, message_attribute_names: ["All"]).messages.first
+
+    expect(sent_message.md5_of_message_attributes).to eq "e3a8318d4639138c2c6fdd04e1f69c8b"
+    expect(sent_message.md5_of_message_attributes).to eq received_message.md5_of_message_attributes
+
+    expect(received_message.message_attributes.keys).to eq ["foo_class"]
+    message_attributes = received_message.message_attributes["foo_class"]
+    expect(message_attributes.string_value).to eq "FooWorker"
+    expect(message_attributes.binary_value).to be_nil
+    expect(message_attributes.string_list_values).to eq []
+    expect(message_attributes.binary_list_values).to eq []
+    expect(message_attributes.data_type).to eq "String"
+  end
+
   specify "ReceiveMessage" do
     body = "test 123"
 
@@ -193,7 +211,7 @@
     )
     expect(nothing.messages.size).to eq 0
 
-    sleep(5)
+    sleep(7)
 
     same_message = sqs.receive_message(
       queue_url: queue_url,
diff --git a/spec/unit/message_spec.rb b/spec/unit/message_spec.rb
index c6e1901..500c768 100644
--- a/spec/unit/message_spec.rb
+++ b/spec/unit/message_spec.rb
@@ -20,6 +20,55 @@
 
   end
 
+  describe "#message_attributes" do
+
+    it "has message attributes" do
+      body = {"MessageBody" => "abc"}
+      attributes = create_attributes [
+          {name: "one", string_value: "A String Value", data_type:"String"},
+          {name: "two", string_value: "35", data_type:"Number"},
+          {name: "three", binary_value: "c29tZSBiaW5hcnkgZGF0YQ==", data_type:"Binary"}
+      ]
+      message = create_message(body.merge attributes)
+
+      expect(message.message_attributes.size).to eq 3
+      expect(message.message_attributes_md5).to eq "6d31a67b8fa3c1a74d030c5de73fd7e2"
+    end
+
+    it "calculates string attribute md5" do
+      body = {"MessageBody" => "abc"}
+      attributes = create_attributes [
+          {name: "one", string_value: "A String Value", data_type:"String"}
+      ]
+      message = create_message(body.merge attributes)
+
+      expect(message.message_attributes_md5).to eq "88bb810f131daa54b83485598cc35693"
+    end
+
+    it "calculates number attribute md5" do
+      body = {"MessageBody" => "abc"}
+      attributes = create_attributes [
+          {name: "two", string_value: "35", data_type:"Number"}
+      ]
+      message = create_message(body.merge attributes)
+
+      expect(message.message_attributes_md5).to eq "7eb7af82e3ed82aef934e78b9ed11f12"
+    end
+
+    it "calculates binary attribute md5" do
+      body = {"MessageBody" => "abc"}
+      attributes = create_attributes [
+          {name: "three", binary_value: "c29tZSBiaW5hcnkgZGF0YQ==", data_type: "Binary"}
+      ]
+      message = create_message(body.merge attributes)
+
+      expect(message.message_attributes_md5).to eq "c0f297612d491707df87d6444ecb4817"
+    end
+
+
+  end
+
+
   describe "#id" do
 
     it "is generated" do
@@ -64,4 +113,17 @@ def create_message(options = {})
     FakeSQS::Message.new({"MessageBody" => "test"}.merge(options))
   end
 
+  def create_attributes(attributes = [])
+    result = {}
+
+    attributes.each_with_index do |attribute, index|
+      result["MessageAttribute.#{index+1}.Name"] = attribute[:name] if attribute[:name]
+      result["MessageAttribute.#{index+1}.Value.StringValue"] = attribute[:string_value] if attribute[:string_value]
+      result["MessageAttribute.#{index+1}.Value.BinaryValue"] = attribute[:binary_value] if attribute[:binary_value]
+      result["MessageAttribute.#{index+1}.Value.DataType"] = attribute[:data_type] if attribute[:data_type]
+    end
+
+    result
+  end
+
 end