diff --git a/lib/bitarray-array.rb b/lib/bitarray-array.rb
deleted file mode 100644
index 2191ffb..0000000
--- a/lib/bitarray-array.rb
+++ /dev/null
@@ -1,51 +0,0 @@
-class BitArray
-  attr_reader :size
-  attr_reader :field
-  include Enumerable
-
-  VERSION = "1.3.0"
-  ELEMENT_WIDTH = 32
-
-  def initialize(size, field = nil)
-    @size = size
-    @field = field || Array.new(((size - 1) / ELEMENT_WIDTH) + 1, 0)
-  end
-
-  # Set a bit (1/0)
-  def []=(position, value)
-    if value == 1
-      @field[position / ELEMENT_WIDTH] |= 1 << (position % ELEMENT_WIDTH)
-    elsif (@field[position / ELEMENT_WIDTH]) & (1 << (position % ELEMENT_WIDTH)) != 0
-      @field[position / ELEMENT_WIDTH] ^= 1 << (position % ELEMENT_WIDTH)
-    end
-  end
-
-  # Read a bit (1/0)
-  def [](position)
-    @field[position / ELEMENT_WIDTH] & 1 << (position % ELEMENT_WIDTH) > 0 ? 1 : 0
-  end
-
-  # Iterate over each bit
-  def each
-    return to_enum unless block_given?
-    @size.times { |position| yield self[position] }
-  end
-
-  # Returns the field as a string like "0101010100111100," etc.
-  def to_s
-    @field.collect{|ea| ("%0#{ELEMENT_WIDTH}b" % ea).reverse}.join[0..@size-1]
-  end
-  
-  # Iterate over each byte
-  def each_byte
-    return to_enum(:each_byte) unless block_given?
-    @field.each { |byte| yield byte }
-  end
-
-  # Returns the total number of bits that are set
-  # Use Brian Kernighan's way, see
-  # https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetKernighan
-  def total_set
-    @field.each_byte.inject(0) { |a, byte| (a += 1; byte &= byte - 1) while byte > 0 ; a }
-  end
-end
diff --git a/lib/bitarray.rb b/lib/bitarray.rb
index 992d753..e70e66c 100644
--- a/lib/bitarray.rb
+++ b/lib/bitarray.rb
@@ -1,59 +1 @@
-class BitArray
-  attr_reader :size
-  attr_reader :field
-  include Enumerable
-
-  VERSION = "1.3.0"
-
-  def initialize(size, field = nil, reverse_byte: true)
-    @size = size
-    @field = field || "\0" * (size / 8 + 1)
-    @reverse_byte = reverse_byte
-  end
-
-  # Set a bit (1/0)
-  def []=(position, value)
-    if value == 1
-      @field.setbyte(position >> 3, @field.getbyte(position >> 3) | (1 << (byte_position(position) % 8)))
-    else
-      @field.setbyte(position >> 3, @field.getbyte(position >> 3) & ~(1 << (byte_position(position) % 8)))
-    end
-  end
-
-  # Read a bit (1/0)
-  def [](position)
-    (@field.getbyte(position >> 3) & (1 << (byte_position(position) % 8))) > 0 ? 1 : 0
-  end
-
-  # Iterate over each bit
-  def each
-    return to_enum(:each) unless block_given?
-    @size.times { |position| yield self[position] }
-  end
-
-  # Returns the field as a string like "0101010100111100," etc.
-  def to_s
-    if @reverse_byte
-      @field.bytes.collect { |ea| ("%08b" % ea).reverse }.join[0, @size]
-    else
-      @field.bytes.collect { |ea| ("%08b" % ea) }.join[0, @size]
-    end
-  end
-  
-  # Iterates over each byte
-  def each_byte
-    return to_enum(:each_byte) unless block_given?
-    @field.bytes.each{ |byte| yield byte }
-  end
-
-  # Returns the total number of bits that are set
-  # Use Brian Kernighan's way, see
-  # https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetKernighan
-  def total_set
-    @field.each_byte.inject(0) { |a, byte| (a += 1; byte &= byte - 1) while byte > 0 ; a }
-  end
-
-  def byte_position(position)
-    @reverse_byte ? position : 7 - position
-  end
-end
+require_relative "bitarray/bit_array"
diff --git a/lib/bitarray/bit_array.rb b/lib/bitarray/bit_array.rb
new file mode 100644
index 0000000..476c34a
--- /dev/null
+++ b/lib/bitarray/bit_array.rb
@@ -0,0 +1,58 @@
+class BitArray
+  attr_reader :field, :reverse_byte, :size
+  include Enumerable
+
+  VERSION = "1.3.0"
+
+  def initialize(size, field = nil, reverse_byte: true)
+    @size = size
+    @field = field || "\0" * (size / 8 + 1)
+    @reverse_byte = reverse_byte
+  end
+
+  # Set a bit (1/0)
+  def []=(position, value)
+    if value == 1
+      @field.setbyte(position >> 3, @field.getbyte(position >> 3) | (1 << (byte_position(position) % 8)))
+    else
+      @field.setbyte(position >> 3, @field.getbyte(position >> 3) & ~(1 << (byte_position(position) % 8)))
+    end
+  end
+
+  # Read a bit (1/0)
+  def [](position)
+    (@field.getbyte(position >> 3) & (1 << (byte_position(position) % 8))) > 0 ? 1 : 0
+  end
+
+  # Iterate over each bit
+  def each
+    return to_enum(:each) unless block_given?
+    @size.times { |position| yield self[position] }
+  end
+
+  # Returns the field as a string like "0101010100111100," etc.
+  def to_s
+    if @reverse_byte
+      @field.bytes.collect { |ea| ("%08b" % ea).reverse }.join[0, @size]
+    else
+      @field.bytes.collect { |ea| ("%08b" % ea) }.join[0, @size]
+    end
+  end
+
+  # Iterates over each byte
+  def each_byte
+    return to_enum(:each_byte) unless block_given?
+    @field.bytes.each{ |byte| yield byte }
+  end
+
+  # Returns the total number of bits that are set
+  # Use Brian Kernighan's way, see
+  # https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetKernighan
+  def total_set
+    @field.each_byte.inject(0) { |a, byte| (a += 1; byte &= byte - 1) while byte > 0 ; a }
+  end
+
+  private def byte_position(position)
+    @reverse_byte ? position : 7 - position
+  end
+end
diff --git a/test/test_bitarray.rb b/test/test_bit_array.rb
similarity index 100%
rename from test/test_bitarray.rb
rename to test/test_bit_array.rb