diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..46e8cea
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,15 @@
+AllCops:
+  TargetRubyVersion: 2.0
+
+LineLength:
+  Description: 'Limit lines to 100 characters.'
+  Max: 100
+  Enabled: true
+
+Metrics/ModuleLength:
+  Exclude:
+    - "**/*_test.rb"
+
+Metrics/BlockLength:
+  Exclude:
+    - "**/*_test.rb"
\ No newline at end of file
diff --git a/Gemfile b/Gemfile
index 38ff725..bdbdcea 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 # Specify your gem's dependencies in tdigest.gemspec
diff --git a/Rakefile b/Rakefile
index d6c5113..2d96143 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,9 +1,11 @@
-require "bundler/gem_tasks"
-require "rake/testtask"
+# frozen_string_literal: true
+
+require 'bundler/gem_tasks'
+require 'rake/testtask'
 
 Rake::TestTask.new(:test) do |t|
-  t.libs << "test"
-  t.libs << "lib"
+  t.libs << 'test'
+  t.libs << 'lib'
   t.test_files = FileList['test/**/*_test.rb']
 end
 
diff --git a/bin/console b/bin/console
index 7e467e0..09eca5f 100755
--- a/bin/console
+++ b/bin/console
@@ -1,7 +1,8 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
-require "bundler/setup"
-require "tdigest"
+require 'bundler/setup'
+require 'tdigest'
 
 # You can add fixtures and/or initialization code here to make experimenting
 # with your gem easier. You can also use a different console, if you like.
@@ -10,5 +11,5 @@ require "tdigest"
 # require "pry"
 # Pry.start
 
-require "irb"
+require 'irb'
 IRB.start
diff --git a/lib/tdigest.rb b/lib/tdigest.rb
index fcd9cfa..288fce4 100644
--- a/lib/tdigest.rb
+++ b/lib/tdigest.rb
@@ -1,5 +1,7 @@
-require "tdigest/version"
-require "tdigest/tdigest"
+# frozen_string_literal: true
+
+require 'tdigest/version'
+require 'tdigest/tdigest'
 
 module TDigest
   # Your code goes here...
diff --git a/lib/tdigest/centroid.rb b/lib/tdigest/centroid.rb
index 3910253..f98aa47 100644
--- a/lib/tdigest/centroid.rb
+++ b/lib/tdigest/centroid.rb
@@ -1,4 +1,7 @@
+# frozen_string_literal: true
+
 module TDigest
+  # Representation of a Centroid
   class Centroid
     attr_accessor :mean, :n, :cumn, :mean_cumn
     def initialize(mean, n, cumn, mean_cumn = nil)
diff --git a/lib/tdigest/tdigest.rb b/lib/tdigest/tdigest.rb
index 5ec1a0a..caeba9b 100644
--- a/lib/tdigest/tdigest.rb
+++ b/lib/tdigest/tdigest.rb
@@ -1,7 +1,10 @@
+# frozen_string_literal: true
+
 require 'rbtree'
 require 'tdigest/centroid'
 
 module TDigest
+  # Main TDigest class
   class TDigest
     VERBOSE_ENCODING = 1
     SMALL_ENCODING   = 2
@@ -20,10 +23,9 @@ def initialize(delta = 0.01, k = 25, cx = 1.1)
     def +(other)
       # Uses delta, k and cx from the caller
       t = self.class.new(@delta, @k, @cx)
-      data = self.centroids.values + other.centroids.values
-      while data.length > 0
-        t.push_centroid(data.delete_at(rand(data.length)))
-      end
+      data = centroids.values + other.centroids.values
+      t.push_centroid(data.delete_at(rand(data.length))) until data.empty?
+
       t
     end
 
@@ -56,7 +58,7 @@ def as_small_bytes
           arr << b
           n = n >> 7
           k += 1
-          fail 'Unreasonable large number' if k > 6
+          raise 'Unreasonable large number' if k > 6
         end
         arr << n
       end
@@ -77,7 +79,7 @@ def bound_mean(x)
     def bound_mean_cumn(cumn)
       last_c = nil
       bounds = []
-      matches = @centroids.each do |k, v|
+      @centroids.each do |_, v|
         if v.mean_cumn == cumn
           bounds << v
           break
@@ -108,7 +110,7 @@ def compression
     end
 
     def find_nearest(x)
-      return nil if size == 0
+      return nil if size.zero?
 
       ceil  = @centroids.upper_bound(x)
       floor = @centroids.lower_bound(x)
@@ -139,7 +141,7 @@ def p_rank(x)
       max = @centroids.last
 
       x.map! do |item|
-        if size == 0
+        if size.zero?
           nil
         elsif item < min[1].mean
           0.0
@@ -163,10 +165,10 @@ def percentile(p)
       is_array = p.is_a? Array
       p = [p] unless is_array
       p.map! do |item|
-        unless (0..1).include? item
-          fail ArgumentError, "p should be in [0,1], got #{item}"
+        unless (0..1).cover? item
+          raise ArgumentError, "p should be in [0,1], got #{item}"
         end
-        if size == 0
+        if size.zero?
           nil
         else
           _cumulate(true)
@@ -219,7 +221,7 @@ def self.from_bytes(bytes)
       case format
       when VERBOSE_ENCODING
         array = bytes[start_idx..-1].unpack("d#{size}L#{size}")
-        means, counts = array.each_slice(size).to_a if array.size > 0
+        means, counts = array.each_slice(size).to_a unless array.empty?
       when SMALL_ENCODING
         means = bytes[start_idx..(start_idx + 4 * size)].unpack("f#{size}")
         # Decode delta encoding of means
@@ -237,7 +239,7 @@ def self.from_bytes(bytes)
           z = 0x7f & v
           shift = 7
           while (v & 0x80) != 0
-            fail 'Shift too large in decode' if shift > 28
+            raise 'Shift too large in decode' if shift > 28
             v = counts_bytes.shift || 0
             z += (v & 0x7f) << shift
             shift += 7
@@ -245,9 +247,9 @@ def self.from_bytes(bytes)
           counts << z
         end
         # This shouldn't happen
-        fail 'Mismatch' unless counts.size == means.size
+        raise 'Mismatch' unless counts.size == means.size
       else
-        fail 'Unknown compression format'
+        raise 'Unknown compression format'
       end
       if means && counts
         means.zip(counts).each { |val| tdigest.push(val[0], val[1]) }
@@ -280,12 +282,12 @@ def _add_weight(nearest, x, n)
 
     def _cumulate(exact = false, force = false)
       unless force
-        factor = if @last_cumulate == 0
-          Float::INFINITY
-        else
-          (@n.to_f / @last_cumulate)
-        end
-        return if @n == @last_cumulate || (!exact && @cx && @cx > (factor))
+        factor = if @last_cumulate.zero?
+                   Float::INFINITY
+                 else
+                   (@n.to_f / @last_cumulate)
+                 end
+        return if @n == @last_cumulate || (!exact && @cx && @cx > factor)
       end
 
       cumn = 0
@@ -318,7 +320,7 @@ def _digest(x, n)
       else
         p = nearest.mean_cumn.to_f / @n
         max_n = (4 * @n * @delta * p * (1 - p)).floor
-        if (max_n - nearest.n >= n)
+        if max_n - nearest.n >= n
           _add_weight(nearest, x, n)
         else
           _new_centroid(x, n, nearest.cumn)
@@ -331,9 +333,7 @@ def _digest(x, n)
       # it may be due to values being inserted in sorted order.
       # We combat that by replaying the centroids in random order,
       # which is what compress! does
-      if @centroids.size > (@k / @delta)
-        compress!
-      end
+      compress! if @centroids.size > (@k / @delta)
 
       nil
     end
diff --git a/lib/tdigest/version.rb b/lib/tdigest/version.rb
index 70974df..303a247 100644
--- a/lib/tdigest/version.rb
+++ b/lib/tdigest/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TDigest
-  VERSION = "0.1.1"
+  VERSION = '0.1.1'
 end
diff --git a/test/tdigest_test.rb b/test/tdigest_test.rb
index 76508d4..fb6b70e 100644
--- a/test/tdigest_test.rb
+++ b/test/tdigest_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class TDigestTest < Minitest::Test
@@ -15,7 +17,7 @@ def test_that_it_has_a_version_number
       10.times { tdigest.push(rand * 100) }
       bytes = tdigest.as_bytes
       new_tdigest = ::TDigest::TDigest.from_bytes(bytes)
-      new_tdigest.percentile(0.9).must_equal tdigest.percentile(0.9)
+      new_tdigest.percentile(0.9).must_equal(tdigest.percentile(0.9))
       new_tdigest.as_bytes.must_equal bytes
     end
 
@@ -40,7 +42,8 @@ def test_that_it_has_a_version_number
       new_tdigest = ::TDigest::TDigest.from_bytes(bytes)
       # Expect some rounding error due to compression
       new_tdigest.percentile(0.9).round(5).must_equal(
-        tdigest.percentile(0.9).round(5))
+        tdigest.percentile(0.9).round(5)
+      )
       new_tdigest.as_small_bytes.must_equal bytes
     end
 
@@ -91,9 +94,9 @@ def test_that_it_has_a_version_number
         tdigest.push(values)
         tdigest.compress!
 
-        0.step(1,0.1).each do |i|
+        0.step(1, 0.1).each do |i|
           q = tdigest.percentile(i)
-          maxerr = [maxerr, (i-q).abs].max
+          maxerr = [maxerr, (i - q).abs].max
         end
 
         assert_operator maxerr, :<, 0.01
@@ -104,7 +107,8 @@ def test_that_it_has_a_version_number
   describe '#push' do
     it "calls _cumulate so won't crash because of uninitialized mean_cumn" do
       td = TDigest::TDigest.new
-      td.push [125000000.0,
+      td.push [
+        125000000.0,
         104166666.66666666,
         135416666.66666666,
         104166666.66666666,
@@ -135,7 +139,8 @@ def test_that_it_has_a_version_number
         113270270.27027026,
         154459459.45945945,
         123829787.23404256,
-        103191489.36170213]
+        103191489.36170213
+      ]
     end
 
     it 'does not blow up if data comes in sorted' do
@@ -184,7 +189,7 @@ def test_that_it_has_a_version_number
 
       it 'has the size of the two digests combined' do
         new_tdigest = tdigest + @other
-        new_tdigest.size.must_equal (tdigest.size + @other.size)
+        new_tdigest.size.must_equal(tdigest.size + @other.size)
       end
     end
   end
@@ -193,7 +198,7 @@ def test_that_it_has_a_version_number
     it 'works with empty tdigests' do
       other = ::TDigest::TDigest.new(0.001, 50, 1.2)
       tdigest.merge!(other)
-      (tdigest).centroids.size.must_equal 0
+      tdigest.centroids.size.must_equal(0)
     end
 
     describe 'with populated tdigests' do
@@ -206,7 +211,7 @@ def test_that_it_has_a_version_number
       end
 
       it 'has the parameters of the calling tdigest' do
-        vars = [:@delta, :@k, :@cs]
+        vars = %i[@delta @k @cs]
         expected = Hash[vars.map { |v| [v, tdigest.instance_variable_get(v)] }]
         tdigest.merge!(@other)
         vars.each do |v|
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c680b50..736cfbc 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
 
 require 'simplecov'