diff --git a/.rubocop.yml b/.rubocop.yml
index defa1c7a..927912ab 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -10,7 +10,7 @@ Performance:
   Enabled: true
 
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 2.5
   NewCops: disable
   Exclude:
     - 'vendor/bundle/**/*'
@@ -18,3 +18,7 @@ AllCops:
 Naming/MethodName:
   Exclude:
     - 'example/server/liquid_servlet.rb'
+
+# Backport https://github.com/Shopify/ruby-style-guide/pull/258
+Layout/BeginEndAlignment:
+  Enabled: true
diff --git a/History.md b/History.md
index 97c88664..507a4a2f 100644
--- a/History.md
+++ b/History.md
@@ -2,6 +2,9 @@
 
 ## 5.0.2 (unreleased)
 
+### Features
+* Add `base64_encode`, `base64_decode`, `base64_url_safe_encode`, and `base64_url_safe_decode` filters (#1450) [Daniel Insley]
+
 ### Fixes
 * Fix support for using a String subclass for the liquid source (#1421) [Dylan Thacker-Smith]
 
diff --git a/lib/liquid/condition.rb b/lib/liquid/condition.rb
index 8b7dd65f..3dd433d6 100644
--- a/lib/liquid/condition.rb
+++ b/lib/liquid/condition.rb
@@ -134,8 +134,8 @@ module Liquid
       # return this as the result.
       return context.evaluate(left) if op.nil?
 
-      left  = context.evaluate(left)
-      right = context.evaluate(right)
+      left  = Liquid::Utils.to_liquid_value(context.evaluate(left))
+      right = Liquid::Utils.to_liquid_value(context.evaluate(right))
 
       operation = self.class.operators[op] || raise(Liquid::ArgumentError, "Unknown operator #{op}")
 
diff --git a/lib/liquid/standardfilters.rb b/lib/liquid/standardfilters.rb
index 059f7406..4413a203 100644
--- a/lib/liquid/standardfilters.rb
+++ b/lib/liquid/standardfilters.rb
@@ -1,10 +1,12 @@
 # frozen_string_literal: true
 
 require 'cgi'
+require 'base64'
 require 'bigdecimal'
 
 module Liquid
   module StandardFilters
+    MAX_INT = (1 << 31) - 1
     HTML_ESCAPE = {
       '&' => '&amp;',
       '>' => '&gt;',
@@ -62,6 +64,26 @@ module Liquid
       result
     end
 
+    def base64_encode(input)
+      Base64.strict_encode64(input.to_s)
+    end
+
+    def base64_decode(input)
+      Base64.strict_decode64(input.to_s)
+    rescue ::ArgumentError
+      raise Liquid::ArgumentError, "invalid base64 provided to base64_decode"
+    end
+
+    def base64_url_safe_encode(input)
+      Base64.urlsafe_encode64(input.to_s)
+    end
+
+    def base64_url_safe_decode(input)
+      Base64.urlsafe_decode64(input.to_s)
+    rescue ::ArgumentError
+      raise Liquid::ArgumentError, "invalid base64 provided to base64_url_safe_decode"
+    end
+
     def slice(input, offset, length = nil)
       offset = Utils.to_integer(offset)
       length = length ? Utils.to_integer(length) : 1
@@ -93,7 +115,13 @@ module Liquid
       words = Utils.to_integer(words)
       words = 1 if words <= 0
 
-      wordlist = input.split(" ", words + 1)
+      wordlist = begin
+        input.split(" ", words + 1)
+      rescue RangeError
+        raise if words + 1 < MAX_INT
+        # e.g. integer #{words} too big to convert to `int'
+        raise Liquid::ArgumentError, "integer #{words} too big for truncatewords"
+      end
       return input if wordlist.length <= words
 
       wordlist.pop
@@ -450,7 +478,7 @@ module Liquid
     #
     def default(input, default_value = '', options = {})
       options = {} unless options.is_a?(Hash)
-      false_check = options['allow_false'] ? input.nil? : !input
+      false_check = options['allow_false'] ? input.nil? : !Liquid::Utils.to_liquid_value(input)
       false_check || (input.respond_to?(:empty?) && input.empty?) ? default_value : input
     end
 
diff --git a/lib/liquid/tags/case.rb b/lib/liquid/tags/case.rb
index ccd69bd9..d6ab64e6 100644
--- a/lib/liquid/tags/case.rb
+++ b/lib/liquid/tags/case.rb
@@ -52,7 +52,14 @@ module Liquid
       @blocks.each do |block|
         if block.else?
           block.attachment.render_to_output_buffer(context, output) if execute_else_block
-        elsif block.evaluate(context)
+          next
+        end
+
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
           execute_else_block = false
           block.attachment.render_to_output_buffer(context, output)
         end
diff --git a/lib/liquid/tags/if.rb b/lib/liquid/tags/if.rb
index 44aea616..f4b57d7d 100644
--- a/lib/liquid/tags/if.rb
+++ b/lib/liquid/tags/if.rb
@@ -50,7 +50,11 @@ module Liquid
 
     def render_to_output_buffer(context, output)
       @blocks.each do |block|
-        if block.evaluate(context)
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
           return block.attachment.render_to_output_buffer(context, output)
         end
       end
diff --git a/lib/liquid/tags/unless.rb b/lib/liquid/tags/unless.rb
index f67f57a9..db725dbf 100644
--- a/lib/liquid/tags/unless.rb
+++ b/lib/liquid/tags/unless.rb
@@ -11,13 +11,21 @@ module Liquid
     def render_to_output_buffer(context, output)
       # First condition is interpreted backwards ( if not )
       first_block = @blocks.first
-      unless first_block.evaluate(context)
+      result = Liquid::Utils.to_liquid_value(
+        first_block.evaluate(context)
+      )
+
+      unless result
         return first_block.attachment.render_to_output_buffer(context, output)
       end
 
       # After the first condition unless works just like if
       @blocks[1..-1].each do |block|
-        if block.evaluate(context)
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
           return block.attachment.render_to_output_buffer(context, output)
         end
       end
diff --git a/lib/liquid/utils.rb b/lib/liquid/utils.rb
index 15a513ff..38a406ef 100644
--- a/lib/liquid/utils.rb
+++ b/lib/liquid/utils.rb
@@ -81,5 +81,13 @@ module Liquid
     rescue ::ArgumentError
       nil
     end
+
+    def self.to_liquid_value(obj)
+      # Enable "obj" to represent itself as a primitive value like integer, string, or boolean
+      return obj.to_liquid_value if obj.respond_to?(:to_liquid_value)
+
+      # Otherwise return the object itself
+      obj
+    end
   end
 end
diff --git a/lib/liquid/variable_lookup.rb b/lib/liquid/variable_lookup.rb
index 48c7d989..9d5dba68 100644
--- a/lib/liquid/variable_lookup.rb
+++ b/lib/liquid/variable_lookup.rb
@@ -40,6 +40,9 @@ module Liquid
       @lookups.each_index do |i|
         key = context.evaluate(@lookups[i])
 
+        # Cast "key" to its liquid value to enable it to act as a primitive value
+        key = Liquid::Utils.to_liquid_value(key)
+
         # If object is a hash- or array-like object we look for the
         # presence of the key and if its available we return it
         if object.respond_to?(:[]) &&
diff --git a/performance/shopify/database.rb b/performance/shopify/database.rb
index 2db6d300..675f3b34 100644
--- a/performance/shopify/database.rb
+++ b/performance/shopify/database.rb
@@ -3,11 +3,19 @@
 require 'yaml'
 
 module Database
+  DATABASE_FILE_PATH = "#{__dir__}/vision.database.yml"
+
   # Load the standard vision toolkit database and re-arrage it to be simply exportable
   # to liquid as assigns. All this is based on Shopify
   def self.tables
     @tables ||= begin
-      db = YAML.load_file("#{__dir__}/vision.database.yml")
+      db =
+        if YAML.respond_to?(:unsafe_load_file) # Only Psych 4+ can use unsafe_load_file
+          # unsafe_load_file is needed for YAML references
+          YAML.unsafe_load_file(DATABASE_FILE_PATH)
+        else
+          YAML.load_file(DATABASE_FILE_PATH)
+        end
 
       # From vision source
       db['products'].each do |product|
diff --git a/test/integration/standard_filter_test.rb b/test/integration/standard_filter_test.rb
index 0bd1db63..f0f40226 100644
--- a/test/integration/standard_filter_test.rb
+++ b/test/integration/standard_filter_test.rb
@@ -145,6 +145,40 @@ class StandardFiltersTest < Minitest::Test
     assert_equal('&lt;strong&gt;Hulk&lt;/strong&gt;', @filters.escape_once('&lt;strong&gt;Hulk</strong>'))
   end
 
+  def test_base64_encode
+    assert_equal('b25lIHR3byB0aHJlZQ==', @filters.base64_encode('one two three'))
+    assert_equal('', @filters.base64_encode(nil))
+  end
+
+  def test_base64_decode
+    assert_equal('one two three', @filters.base64_decode('b25lIHR3byB0aHJlZQ=='))
+
+    exception = assert_raises(Liquid::ArgumentError) do
+      @filters.base64_decode("invalidbase64")
+    end
+
+    assert_equal('Liquid error: invalid base64 provided to base64_decode', exception.message)
+  end
+
+  def test_base64_url_safe_encode
+    assert_equal(
+      'YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXogQUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVogMTIzNDU2Nzg5MCAhQCMkJV4mKigpLT1fKy8_Ljo7W117fVx8',
+      @filters.base64_url_safe_encode('abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 !@#$%^&*()-=_+/?.:;[]{}\|')
+    )
+    assert_equal('', @filters.base64_url_safe_encode(nil))
+  end
+
+  def test_base64_url_safe_decode
+    assert_equal(
+      'abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ 1234567890 !@#$%^&*()-=_+/?.:;[]{}\|',
+      @filters.base64_url_safe_decode('YWJjZGVmZ2hpamtsbW5vcHFyc3R1dnd4eXogQUJDREVGR0hJSktMTU5PUFFSU1RVVldYWVogMTIzNDU2Nzg5MCAhQCMkJV4mKigpLT1fKy8_Ljo7W117fVx8')
+    )
+    exception = assert_raises(Liquid::ArgumentError) do
+      @filters.base64_url_safe_decode("invalidbase64")
+    end
+    assert_equal('Liquid error: invalid base64 provided to base64_url_safe_decode', exception.message)
+  end
+
   def test_url_encode
     assert_equal('foo%2B1%40example.com', @filters.url_encode('foo+1@example.com'))
     assert_equal('1', @filters.url_encode(1))
@@ -178,6 +212,10 @@ class StandardFiltersTest < Minitest::Test
     assert_equal('one two three...', @filters.truncatewords("one  two\tthree\nfour", 3))
     assert_equal('one two...', @filters.truncatewords("one two three four", 2))
     assert_equal('one...', @filters.truncatewords("one two three four", 0))
+    exception = assert_raises(Liquid::ArgumentError) do
+      @filters.truncatewords("one two three four", 1 << 31)
+    end
+    assert_equal("Liquid error: integer #{1 << 31} too big for truncatewords", exception.message)
   end
 
   def test_strip_html
@@ -704,6 +742,8 @@ class StandardFiltersTest < Minitest::Test
     assert_equal("bar", @filters.default([], "bar"))
     assert_equal("bar", @filters.default({}, "bar"))
     assert_template_result('bar', "{{ false | default: 'bar' }}")
+    assert_template_result('bar', "{{ drop | default: 'bar' }}", 'drop' => BooleanDrop.new(false))
+    assert_template_result('Yay', "{{ drop | default: 'bar' }}", 'drop' => BooleanDrop.new(true))
   end
 
   def test_default_handle_false
@@ -714,6 +754,8 @@ class StandardFiltersTest < Minitest::Test
     assert_equal("bar", @filters.default([], "bar", "allow_false" => true))
     assert_equal("bar", @filters.default({}, "bar", "allow_false" => true))
     assert_template_result('false', "{{ false | default: 'bar', allow_false: true }}")
+    assert_template_result('Nay', "{{ drop | default: 'bar', allow_false: true }}", 'drop' => BooleanDrop.new(false))
+    assert_template_result('Yay', "{{ drop | default: 'bar', allow_false: true }}", 'drop' => BooleanDrop.new(true))
   end
 
   def test_cannot_access_private_methods
diff --git a/test/integration/variable_test.rb b/test/integration/variable_test.rb
index dd34d71f..5c875501 100644
--- a/test/integration/variable_test.rb
+++ b/test/integration/variable_test.rb
@@ -15,6 +15,33 @@ class VariableTest < Minitest::Test
     assert_template_result('foobar', '{{ foo }}', 'foo' => ThingWithToLiquid.new)
   end
 
+  def test_variable_lookup_calls_to_liquid_value
+    assert_template_result('1', '{{ foo }}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('2', '{{ list[foo] }}', 'foo' => IntegerDrop.new('1'), 'list' => [1, 2, 3])
+    assert_template_result('one', '{{ list[foo] }}', 'foo' => IntegerDrop.new('1'), 'list' => { 1 => 'one' })
+    assert_template_result('Yay', '{{ foo }}', 'foo' => BooleanDrop.new(true))
+    assert_template_result('YAY', '{{ foo | upcase }}', 'foo' => BooleanDrop.new(true))
+  end
+
+  def test_if_tag_calls_to_liquid_value
+    assert_template_result('one', '{% if foo == 1 %}one{% endif %}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('one', '{% if 0 < foo %}one{% endif %}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('one', '{% if foo > 0 %}one{% endif %}', 'foo' => IntegerDrop.new('1'))
+    assert_template_result('true', '{% if foo == true %}true{% endif %}', 'foo' => BooleanDrop.new(true))
+    assert_template_result('true', '{% if foo %}true{% endif %}', 'foo' => BooleanDrop.new(true))
+
+    assert_template_result('', '{% if foo %}true{% endif %}', 'foo' => BooleanDrop.new(false))
+    assert_template_result('', '{% if foo == true %}True{% endif %}', 'foo' => BooleanDrop.new(false))
+  end
+
+  def test_unless_tag_calls_to_liquid_value
+    assert_template_result('', '{% unless foo %}true{% endunless %}', 'foo' => BooleanDrop.new(true))
+  end
+
+  def test_case_tag_calls_to_liquid_value
+    assert_template_result('One', '{% case foo %}{% when 1 %}One{% endcase %}', 'foo' => IntegerDrop.new('1'))
+  end
+
   def test_simple_with_whitespaces
     template = Template.parse(%(  {{ test }}  ))
     assert_equal('  worked  ', template.render!('test' => 'worked'))
@@ -104,4 +131,8 @@ class VariableTest < Minitest::Test
   def test_dynamic_find_var
     assert_template_result('bar', '{{ [key] }}', 'key' => 'foo', 'foo' => 'bar')
   end
+
+  def test_raw_value_variable
+    assert_template_result('bar', '{{ [key] }}', 'key' => 'foo', 'foo' => 'bar')
+  end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 5afd10f0..f5c1c6a6 100755
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -119,6 +119,44 @@ class ThingWithToLiquid
   end
 end
 
+class IntegerDrop < Liquid::Drop
+  def initialize(value)
+    super()
+    @value = value.to_i
+  end
+
+  def ==(other)
+    @value == other
+  end
+
+  def to_s
+    @value.to_s
+  end
+
+  def to_liquid_value
+    @value
+  end
+end
+
+class BooleanDrop < Liquid::Drop
+  def initialize(value)
+    super()
+    @value = value
+  end
+
+  def ==(other)
+    @value == other
+  end
+
+  def to_liquid_value
+    @value
+  end
+
+  def to_s
+    @value ? "Yay" : "Nay"
+  end
+end
+
 class ErrorDrop < Liquid::Drop
   def standard_error
     raise Liquid::StandardError, 'standard error'