diff --git a/lib/sphero/request.rb b/lib/sphero/request.rb
index 2ff0857..b7651fe 100644
--- a/lib/sphero/request.rb
+++ b/lib/sphero/request.rb
@@ -31,7 +31,8 @@ def response header, body
     end
 
     def packet_header
-      header.pack 'CCCCCC'
+      format = "C" * header.length
+      header.pack format
     end
 
     def packet_body
@@ -39,7 +40,11 @@ def packet_body
     end
 
     def checksum
-      ~((packet_header + packet_body).unpack('C*').drop(2).reduce(:+) % 256) & 0xFF
+      unpacked_header_and_body = (packet_header + packet_body).unpack "C*"
+      dropped_sops = unpacked_header_and_body.drop 2
+      reduced = dropped_sops.reduce(:+) % 256
+      ones_complement = ~reduced
+      ones_complement & 0xFF
     end
 
     def bytes
diff --git a/test/test_request.rb b/test/test_request.rb
new file mode 100644
index 0000000..db12282
--- /dev/null
+++ b/test/test_request.rb
@@ -0,0 +1,49 @@
+require 'minitest/autorun'
+require 'sphero/request'
+
+class TestRequest < MiniTest::Unit::TestCase
+  STUB_REQUEST_ID = 0x05
+
+  def setup
+    @stub_request_class = Sphero::Request.
+      make_command Sphero::Request, STUB_REQUEST_ID
+  end
+
+  def test_request_checksum
+    stub_request = @stub_request_class.new 0x01, 1, 2
+    assert_equal 243, stub_request.checksum
+  end
+
+  def test_packet_body
+    auto_reconnect = @stub_request_class.new 0x01, 0, 0x00
+    assert_equal [0, 0x00].pack("C*"), auto_reconnect.packet_body
+  end
+
+  def test_request_dlen
+    auto_reconnect = @stub_request_class.new 0x01, 0, 0x00
+    assert_equal 3, auto_reconnect.dlen
+  end
+
+  def test_request_header
+    stub_request = @stub_request_class.new 0x01, 1, 2
+    expected_header = [Sphero::Request::SOP1, Sphero::Request::SOP2, 
+                       0x00, STUB_REQUEST_ID, 0x01, 3]
+
+    assert_equal expected_header, stub_request.header
+  end
+
+  def test_ping_to_str
+    ping = Sphero::Request::Ping.new 0
+    assert_equal "\xFF\xFF\x00\x01\x00\x01\xFD", ping.to_str
+  end
+
+  def test_ping_checksum
+    ping = Sphero::Request::Ping.new 0
+    assert_equal "\xFD", ping.checksum.chr
+  end
+
+  def test_sleep_dlen
+    sleep = Sphero::Request::Sleep.new 0, 0, 0
+    assert_equal 0x04, sleep.dlen
+  end
+end
diff --git a/test/test_sphero.rb b/test/test_sphero.rb
deleted file mode 100644
index ecdca09..0000000
--- a/test/test_sphero.rb
+++ /dev/null
@@ -1,14 +0,0 @@
-require 'minitest/autorun'
-require 'sphero'
-
-class TestSphero < MiniTest::Unit::TestCase
-  def test_ping_checksum
-    ping = Sphero::Request::Ping.new 0
-    assert_equal "\xFF\xFF\x00\x01\x00\x01\xFD".bytes, ping.to_str.bytes
-  end
-
-  def test_sleep_dlen
-    sleep = Sphero::Request::Sleep.new 0, 0, 0
-    assert_equal 0x04, sleep.dlen
-  end
-end