diff --git a/.rubocop.yml b/.rubocop.yml
index 310aa0c8..9544655c 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -44,7 +44,7 @@ Style/GuardClause:
   MinBodyLength: 4
 
 Style/HashSyntax:
-  EnforcedStyle: hash_rockets
+  Enabled: False
 
 Style/IndentHash:
   EnforcedStyle: consistent
diff --git a/lib/protobuf.rb b/lib/protobuf.rb
index 69139e2c..ccd22ccf 100644
--- a/lib/protobuf.rb
+++ b/lib/protobuf.rb
@@ -1,14 +1,27 @@
 require 'base64'
+require 'json'
 require 'logger'
 require 'pp'
 require 'socket'
 require 'stringio'
 
-require 'active_support/core_ext/object/blank'
-require 'active_support/core_ext/object/try'
-require 'active_support/inflector'
-require 'active_support/json'
-require 'active_support/notifications'
+# rubocop:disable Lint/HandleExceptions
+begin
+  require 'active_support/lazy_load_hooks'
+rescue LoadError
+end
+begin
+  require 'active_support/notifications'
+rescue LoadError
+end
+# rubocop:enable Lint/HandleExceptions
+
+require 'protobuf/refinements/string/classify'
+require 'protobuf/refinements/string/constantize'
+
+using Protobuf::Refinements::String::Classify
+using Protobuf::Refinements::String::Constantize
+
 # Under MRI, this optimizes proto decoding by around 15% in tests.
 # When unavailable, we fall to pure Ruby.
 # rubocop:disable Lint/HandleExceptions
@@ -55,17 +68,33 @@ class << self
   end
 
   def self.after_server_bind(&block)
+    unless Object.const_defined?('::ActiveSupport::Notifications')
+      warn_no_active_support_notifications('after_server_bind')
+      return
+    end
+
     ::ActiveSupport::Notifications.subscribe('after_server_bind') do |*args|
       block.call(*args)
     end
   end
 
   def self.before_server_bind(&block)
+    unless Object.const_defined?('::ActiveSupport::Notifications')
+      warn_no_active_support_notifications('before_server_bind')
+      return
+    end
+
     ::ActiveSupport::Notifications.subscribe('before_server_bind') do |*args|
       block.call(*args)
     end
   end
 
+  def self.warn_no_active_support_notifications(method)
+    return if ENV['PROTOBUF_SUPPRESS_NO_ACTIVE_SUPPORT_NOTIFICATIONS_WARNING'] == '1'
+
+    STDERR.puts("[WARN] ActiveSupport::Notifications is not loaded. To use `Protobuf.#{method}`, you need to require 'active_support/notifications'")
+  end
+
   def self.client_host
     @client_host ||= Socket.gethostname
   end
diff --git a/lib/protobuf/cli.rb b/lib/protobuf/cli.rb
index 35c6d936..c1bb6c11 100644
--- a/lib/protobuf/cli.rb
+++ b/lib/protobuf/cli.rb
@@ -1,11 +1,15 @@
-require 'active_support/core_ext/hash/keys'
-require 'active_support/inflector'
-
 require 'thor'
 require 'protobuf/version'
 require 'protobuf/logging'
 require 'protobuf/rpc/servers/socket_runner'
 require 'protobuf/rpc/servers/zmq_runner'
+require 'protobuf/refinements/hash/symbolize_keys'
+require 'protobuf/refinements/string/classify'
+require 'protobuf/refinements/string/constantize'
+
+using Protobuf::Refinements::Hash::SymbolizeKeys
+using Protobuf::Refinements::String::Classify
+using Protobuf::Refinements::String::Constantize
 
 module Protobuf
   class CLI < ::Thor
@@ -240,14 +244,14 @@ def shutdown_server
       def start_server
         debug_say('Running server')
 
-        ::ActiveSupport::Notifications.instrument("before_server_bind")
+        ::ActiveSupport::Notifications.instrument("before_server_bind") if Object.const_defined?('::ActiveSupport::Notifications')
 
         runner.run do
           logger.info do
             "pid #{::Process.pid} -- #{mode} RPC Server listening at #{options.host}:#{options.port}"
           end
 
-          ::ActiveSupport::Notifications.instrument("after_server_bind")
+          ::ActiveSupport::Notifications.instrument("after_server_bind") if Object.const_defined?('::ActiveSupport::Notifications')
         end
 
         logger.info { 'Shutdown complete' }
diff --git a/lib/protobuf/code_generator.rb b/lib/protobuf/code_generator.rb
index 7b04a32c..8ef70ba2 100644
--- a/lib/protobuf/code_generator.rb
+++ b/lib/protobuf/code_generator.rb
@@ -1,4 +1,3 @@
-require 'active_support/core_ext/module/aliasing'
 require 'protobuf/generators/file_generator'
 
 module Protobuf
diff --git a/lib/protobuf/deprecation.rb b/lib/protobuf/deprecation.rb
index 8c0d415e..d1bc1328 100644
--- a/lib/protobuf/deprecation.rb
+++ b/lib/protobuf/deprecation.rb
@@ -1,7 +1,20 @@
-require 'active_support/deprecation'
+begin
+  require 'active_support/deprecation'
+rescue LoadError # rubocop:disable Lint/HandleExceptions
+end
 
 module Protobuf
-  if ::ActiveSupport::Deprecation.is_a?(Class)
+  if !Object.const_defined?('::ActiveSupport::Deprecation')
+    class NullDeprecator
+      def initialize(*); end
+      def define_deprecated_methods(*); end
+      def deprecate_methods(*); end
+      attr_accessor :silenced, :behavior
+    end
+
+    Deprecation = NullDeprecator.clone
+    FieldDeprecation = NullDeprecator.clone
+  elsif ::ActiveSupport::Deprecation.is_a?(Class)
     class DeprecationBase < ::ActiveSupport::Deprecation
       def deprecate_methods(*args)
         deprecation_options = { :deprecator => self }
diff --git a/lib/protobuf/enum.rb b/lib/protobuf/enum.rb
index c0a2a809..beba312f 100644
--- a/lib/protobuf/enum.rb
+++ b/lib/protobuf/enum.rb
@@ -1,5 +1,9 @@
 require 'delegate'
 
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
+
 ##
 # Adding extension to Numeric until
 # we can get people to stop calling #value
diff --git a/lib/protobuf/field/base_field.rb b/lib/protobuf/field/base_field.rb
index 6f2f4f7f..6341ae88 100644
--- a/lib/protobuf/field/base_field.rb
+++ b/lib/protobuf/field/base_field.rb
@@ -1,7 +1,9 @@
-require 'active_support/core_ext/hash/slice'
 require 'protobuf/field/field_array'
 require 'protobuf/field/field_hash'
 require 'protobuf/field/base_field_object_definitions'
+require 'protobuf/refinements/hash/slice'
+
+using Protobuf::Refinements::Hash::Slice
 
 module Protobuf
   module Field
diff --git a/lib/protobuf/field/base_field_object_definitions.rb b/lib/protobuf/field/base_field_object_definitions.rb
index 93a93226..8a3dba1d 100644
--- a/lib/protobuf/field/base_field_object_definitions.rb
+++ b/lib/protobuf/field/base_field_object_definitions.rb
@@ -1,3 +1,7 @@
+require 'protobuf/refinements/kernel/blank'
+
+using Protobuf::Refinements::Kernel::Blank
+
 module Protobuf
   module Field
     module BaseFieldObjectDefinitions
diff --git a/lib/protobuf/field/bytes_field.rb b/lib/protobuf/field/bytes_field.rb
index e120835c..eb687e89 100644
--- a/lib/protobuf/field/bytes_field.rb
+++ b/lib/protobuf/field/bytes_field.rb
@@ -70,7 +70,7 @@ def coerce!(value)
         end
       end
 
-      def json_encode(value, options={})
+      def json_encode(value, _options = {})
         Base64.strict_encode64(value)
       end
     end
diff --git a/lib/protobuf/field/enum_field.rb b/lib/protobuf/field/enum_field.rb
index 12867adf..add8bf06 100644
--- a/lib/protobuf/field/enum_field.rb
+++ b/lib/protobuf/field/enum_field.rb
@@ -37,7 +37,7 @@ def coerce!(value)
         type_class.fetch(value) || fail(TypeError, "Invalid Enum value: #{value.inspect} for #{name}")
       end
 
-      def json_encode(value, options={})
+      def json_encode(value, _options = {})
         enum = type_class.enums.find { |e| e.to_i == value }
         enum.to_s(:name)
       end
diff --git a/lib/protobuf/field/string_field.rb b/lib/protobuf/field/string_field.rb
index 551bdd23..08dc1136 100644
--- a/lib/protobuf/field/string_field.rb
+++ b/lib/protobuf/field/string_field.rb
@@ -43,7 +43,7 @@ def encode(value)
         "#{::Protobuf::Field::VarintField.encode(value_to_encode.bytesize)}#{value_to_encode}"
       end
 
-      def json_encode(value, options={})
+      def json_encode(value, _options = {})
         value
       end
     end
diff --git a/lib/protobuf/generators/enum_generator.rb b/lib/protobuf/generators/enum_generator.rb
index 1088e3ed..9b836ddc 100644
--- a/lib/protobuf/generators/enum_generator.rb
+++ b/lib/protobuf/generators/enum_generator.rb
@@ -1,5 +1,8 @@
 require 'protobuf/generators/base'
 require 'protobuf/generators/option_generator'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Generators
diff --git a/lib/protobuf/generators/field_generator.rb b/lib/protobuf/generators/field_generator.rb
index 68652fcc..c718d90a 100644
--- a/lib/protobuf/generators/field_generator.rb
+++ b/lib/protobuf/generators/field_generator.rb
@@ -1,4 +1,7 @@
 require 'protobuf/generators/base'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Generators
diff --git a/lib/protobuf/generators/file_generator.rb b/lib/protobuf/generators/file_generator.rb
index f94d2264..18af88d5 100644
--- a/lib/protobuf/generators/file_generator.rb
+++ b/lib/protobuf/generators/file_generator.rb
@@ -1,6 +1,9 @@
 require 'set'
 require 'protobuf/generators/base'
 require 'protobuf/generators/group_generator'
+require 'protobuf/refinements/string/constantize'
+
+using Protobuf::Refinements::String::Constantize
 
 module Protobuf
   module Generators
diff --git a/lib/protobuf/generators/group_generator.rb b/lib/protobuf/generators/group_generator.rb
index 33e7b5be..81b81683 100644
--- a/lib/protobuf/generators/group_generator.rb
+++ b/lib/protobuf/generators/group_generator.rb
@@ -4,6 +4,9 @@
 require 'protobuf/generators/message_generator'
 require 'protobuf/generators/option_generator'
 require 'protobuf/generators/service_generator'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Generators
diff --git a/lib/protobuf/generators/service_generator.rb b/lib/protobuf/generators/service_generator.rb
index f7e9febd..a65d991b 100644
--- a/lib/protobuf/generators/service_generator.rb
+++ b/lib/protobuf/generators/service_generator.rb
@@ -1,5 +1,8 @@
 require 'protobuf/generators/base'
 require 'protobuf/generators/option_generator'
+require 'protobuf/refinements/string/underscore'
+
+using Protobuf::Refinements::String::Underscore
 
 module Protobuf
   module Generators
diff --git a/lib/protobuf/lifecycle.rb b/lib/protobuf/lifecycle.rb
index a17aac5c..96ee5501 100644
--- a/lib/protobuf/lifecycle.rb
+++ b/lib/protobuf/lifecycle.rb
@@ -5,8 +5,10 @@ def register(event_name)
         fail "Lifecycle register must have a block" unless block_given?
         event_name = normalized_event_name(event_name)
 
-        ::ActiveSupport::Notifications.subscribe(event_name) do |_name, _start, _finish, _id, args|
-          yield(*args)
+        if Object.const_defined?('::ActiveSupport::Notifications')
+          ::ActiveSupport::Notifications.subscribe(event_name) do |_name, _start, _finish, _id, args|
+            yield(*args)
+          end
         end
       end
       alias :on register
@@ -14,16 +16,18 @@ def register(event_name)
       def trigger(event_name, *args)
         event_name = normalized_event_name(event_name)
 
-        ::ActiveSupport::Notifications.instrument(event_name, args)
+        ::ActiveSupport::Notifications.instrument(event_name, args) if Object.const_defined?('::ActiveSupport::Notifications')
       end
 
-      replacement = ::ActiveSupport::Notifications
+      if Object.const_defined?('::ActiveSupport::Notifications')
+        replacement = ::ActiveSupport::Notifications
 
-      ::Protobuf.deprecator.deprecate_methods(
-        self,
-        :register => "#{replacement}.#{replacement.method(:subscribe).name}".to_sym,
-        :trigger => "#{replacement}.#{replacement.method(:instrument).name}".to_sym,
-      )
+        ::Protobuf.deprecator.deprecate_methods(
+          self,
+          :register => "#{replacement}.#{replacement.method(:subscribe).name}".to_sym,
+          :trigger => "#{replacement}.#{replacement.method(:instrument).name}".to_sym,
+        )
+      end
 
       def normalized_event_name(event_name)
         event_name.to_s.downcase
diff --git a/lib/protobuf/message.rb b/lib/protobuf/message.rb
index b5b723f5..80eda29a 100644
--- a/lib/protobuf/message.rb
+++ b/lib/protobuf/message.rb
@@ -1,6 +1,11 @@
 require 'protobuf/message/fields'
 require 'protobuf/message/serialization'
 require 'protobuf/varint'
+require 'protobuf/refinements/string/camelize'
+require 'protobuf/refinements/string/underscore'
+
+using Protobuf::Refinements::String::Camelize
+using Protobuf::Refinements::String::Underscore
 
 module Protobuf
   class Message
@@ -174,7 +179,17 @@ def to_json_hash(options = {})
                          value
                        end
 
-        if proto3 && (hashed_value.nil? || value == field.class.default rescue field.default rescue nil)
+        if proto3 && (
+            begin
+              begin
+                hashed_value.nil? || value == field.class.default
+              rescue
+                field.default
+              end
+            rescue
+              nil
+            end
+        )
           result.delete(field.name)
         else
           key = proto3 ? field.name.to_s.camelize(:lower).to_sym : field.name
diff --git a/lib/protobuf/message/fields.rb b/lib/protobuf/message/fields.rb
index d07e1eff..f1c9d3a3 100644
--- a/lib/protobuf/message/fields.rb
+++ b/lib/protobuf/message/fields.rb
@@ -1,4 +1,9 @@
 require "set"
+require 'protobuf/refinements/kernel/blank'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Kernel::Blank
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   class Message
diff --git a/lib/protobuf/optionable.rb b/lib/protobuf/optionable.rb
index 34b00c93..e6dc0a6f 100644
--- a/lib/protobuf/optionable.rb
+++ b/lib/protobuf/optionable.rb
@@ -1,3 +1,7 @@
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Optionable
     module ClassMethods
diff --git a/lib/protobuf/refinements/hash/slice.rb b/lib/protobuf/refinements/hash/slice.rb
new file mode 100644
index 00000000..95efdb85
--- /dev/null
+++ b/lib/protobuf/refinements/hash/slice.rb
@@ -0,0 +1,36 @@
+# Adapted from: https://github.com/rubyworks/facets/blob/master/lib/core/facets/hash/slice.rb
+
+module Protobuf
+  module Refinements
+    module Hash
+      module Slice
+        refine ::Hash do
+          def slice(*keep_keys)
+            if block_given?
+              each do |k, v|
+                keep_keys << k if yield(k, v)
+              end
+            end
+
+            keep_keys.each_with_object({}) do |key, hash|
+              hash[key] = fetch(key) if key?(key)
+            end
+          end
+
+          def slice!(*keep_keys)
+            if block_given?
+              each do |k, v|
+                keep_keys << k if yield(k, v)
+              end
+            end
+
+            rejected = keys - keep_keys
+            removed = {}
+            rejected.each { |k| removed[k] = delete(k) }
+            removed
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/hash/symbolize_keys.rb b/lib/protobuf/refinements/hash/symbolize_keys.rb
new file mode 100644
index 00000000..205003d0
--- /dev/null
+++ b/lib/protobuf/refinements/hash/symbolize_keys.rb
@@ -0,0 +1,21 @@
+# Adapted from: https://github.com/rails/rails/blob/v6.0.3.2/activesupport/lib/active_support/core_ext/hash/keys.rb
+
+module Protobuf
+  module Refinements
+    module Hash
+      module SymbolizeKeys
+        refine ::Hash do
+          def symbolize_keys
+            transform_keys do |key|
+              begin
+                key.to_sym
+              rescue
+                key
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/kernel/blank.rb b/lib/protobuf/refinements/kernel/blank.rb
new file mode 100644
index 00000000..e9dd480b
--- /dev/null
+++ b/lib/protobuf/refinements/kernel/blank.rb
@@ -0,0 +1,70 @@
+# Adapted from: https://github.com/rubyworks/facets/blob/master/lib/core/facets/kernel/blank.rb
+
+module Protobuf
+  module Refinements
+    module Kernel
+      module Blank
+        refine ::Kernel do
+          def blank?
+            return empty? if respond_to?(:empty?)
+            !self
+          end
+
+          def present?
+            !blank?
+          end
+
+          def presence
+            self if present?
+          end
+        end
+
+        refine ::NilClass do
+          def blank?
+            true
+          end
+        end
+
+        refine ::FalseClass do
+          def blank?
+            true
+          end
+        end
+
+        refine ::TrueClass do
+          def blank?
+            false
+          end
+        end
+
+        refine ::Array do
+          alias_method :blank?, :empty?
+        end
+
+        refine ::Hash do
+          alias_method :blank?, :empty?
+        end
+
+        refine ::String do
+          def blank?
+            /\S/ !~ self
+          end
+        end
+
+        refine ::Numeric do
+          def blank?
+            false
+          end
+        end
+
+        if Object.const_defined?('::Delegator')
+          refine ::Delegator do
+            def present?
+              __getobj__.present?
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/object/try.rb b/lib/protobuf/refinements/object/try.rb
new file mode 100644
index 00000000..e2e6bba8
--- /dev/null
+++ b/lib/protobuf/refinements/object/try.rb
@@ -0,0 +1,57 @@
+# Adapted from: https://github.com/rails/rails/blob/v6.0.3.2/activesupport/lib/active_support/core_ext/object/try.rb
+
+module Protobuf
+  module Refinements
+    module Object
+      module Try
+        module Tryable #:nodoc:
+          def try(method_name = nil, *args, &b)
+            if method_name.nil? && block_given?
+              if b.arity == 0
+                instance_eval(&b)
+              else
+                yield self
+              end
+            elsif respond_to?(method_name)
+              public_send(method_name, *args, &b)
+            end
+          end
+          ruby2_keywords(:try) if respond_to?(:ruby2_keywords, true)
+
+          def try!(method_name = nil, *args, &b)
+            if method_name.nil? && block_given?
+              if b.arity == 0
+                instance_eval(&b)
+              else
+                yield self
+              end
+            else
+              public_send(method_name, *args, &b)
+            end
+          end
+          ruby2_keywords(:try!) if respond_to?(:ruby2_keywords, true)
+        end
+
+        refine ::Object do
+          include Tryable
+        end
+
+        if Object.const_defined?('::Delegator')
+          refine ::Delegator do
+            include Tryable
+          end
+        end
+
+        refine ::NilClass do
+          def try(_method_name = nil, *_args)
+            nil
+          end
+
+          def try!(_method_name = nil, *_args)
+            nil
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/string/camelize.rb b/lib/protobuf/refinements/string/camelize.rb
new file mode 100644
index 00000000..7505974d
--- /dev/null
+++ b/lib/protobuf/refinements/string/camelize.rb
@@ -0,0 +1,35 @@
+# Adapted from: https://github.com/rubyworks/facets/blob/master/lib/core/facets/string/camelcase.rb
+
+module Protobuf
+  module Refinements
+    module String
+      module Camelize
+        refine ::String do
+          def camelize(*separators)
+            case separators.first
+            when Symbol, TrueClass, FalseClass, NilClass
+              first_letter = separators.shift
+            end
+
+            separators = ['_', '\s'] if separators.empty?
+
+            str = dup
+
+            separators.each do |s|
+              str = str.gsub(/(?:#{s}+)([a-z])/) { $1.upcase } # rubocop:disable Style/PerlBackrefs
+            end
+
+            case first_letter
+            when :upper, true
+              str = str.gsub(/(\A|\s)([a-z])/) { $1 + $2.upcase } # rubocop:disable Style/PerlBackrefs
+            when :lower, false
+              str = str.gsub(/(\A|\s)([A-Z])/) { $1 + $2.downcase } # rubocop:disable Style/PerlBackrefs
+            end
+
+            str
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/string/classify.rb b/lib/protobuf/refinements/string/classify.rb
new file mode 100644
index 00000000..616efac6
--- /dev/null
+++ b/lib/protobuf/refinements/string/classify.rb
@@ -0,0 +1,19 @@
+# Adapted from: https://github.com/rails/rails/blob/v6.0.3.2/activesupport/lib/active_support/inflector/methods.rb
+
+require 'protobuf/refinements/string/camelize'
+
+module Protobuf
+  module Refinements
+    module String
+      module Classify
+        refine ::String do
+          using Protobuf::Refinements::String::Camelize
+
+          def classify
+            split('/').map { |c| c.camelize(:upper) }.join('::')
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/string/constantize.rb b/lib/protobuf/refinements/string/constantize.rb
new file mode 100644
index 00000000..c0d75f18
--- /dev/null
+++ b/lib/protobuf/refinements/string/constantize.rb
@@ -0,0 +1,53 @@
+# Adapted from: https://github.com/rails/rails/blob/v6.0.3.2/activesupport/lib/active_support/inflector/methods.rb
+
+module Protobuf
+  module Refinements
+    module String
+      module Constantize
+        refine ::String do
+          def constantize
+            names = split("::")
+
+            # Trigger a built-in NameError exception including the ill-formed constant in the message.
+            Object.const_get(self) if names.empty?
+
+            # Remove the first blank element in case of '::ClassName' notation.
+            names.shift if names.size > 1 && names.first.empty?
+
+            names.inject(Object) do |constant, name|
+              if constant == Object
+                constant.const_get(name)
+              else
+                candidate = constant.const_get(name)
+                next candidate if constant.const_defined?(name, false)
+                next candidate unless Object.const_defined?(name)
+
+                # Go down the ancestors to check if it is owned directly. The check
+                # stops when we reach Object or the end of ancestors tree.
+                constant = constant.ancestors.inject(constant) do |const, ancestor| # rubocop:disable Style/EachWithObject
+                  break const    if ancestor == Object
+                  break ancestor if ancestor.const_defined?(name, false)
+                  const
+                end
+
+                # owner is in Object, so raise
+                constant.const_get(name, false)
+              end
+            end
+          end
+
+          def safe_constantize
+            constantize
+          rescue NameError => e
+            raise if e.name && !(to_s.split("::").include?(e.name.to_s) ||
+              e.name.to_s == to_s)
+          rescue ArgumentError => e
+            raise unless /not missing constant #{const_regexp(self)}!$/.match?(e.message)
+          rescue LoadError => e
+            raise unless /Unable to autoload constant #{const_regexp(self)}/.match?(e.message)
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/refinements/string/underscore.rb b/lib/protobuf/refinements/string/underscore.rb
new file mode 100644
index 00000000..62a88620
--- /dev/null
+++ b/lib/protobuf/refinements/string/underscore.rb
@@ -0,0 +1,20 @@
+# Adapted from: https://github.com/rubyworks/facets/blob/master/lib/core/facets/string/snakecase.rb
+
+module Protobuf
+  module Refinements
+    module String
+      module Underscore
+        refine ::String do
+          def underscore(*_separators)
+            gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
+              .gsub(/([a-z\d])([A-Z])/, '\1_\2')
+              .tr('-', '_')
+              .gsub(/\s/, '_')
+              .gsub(/__+/, '_')
+              .downcase
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/lib/protobuf/rpc/client.rb b/lib/protobuf/rpc/client.rb
index 74791d23..3e6c1cb5 100644
--- a/lib/protobuf/rpc/client.rb
+++ b/lib/protobuf/rpc/client.rb
@@ -135,6 +135,6 @@ def method_missing(method_name, *params)
 
     end
 
-    ActiveSupport.run_load_hooks(:protobuf_rpc_client, Client)
+    ActiveSupport.run_load_hooks(:protobuf_rpc_client, Client) if Object.const_defined?('::ActiveSupport::LazyLoadHooks')
   end
 end
diff --git a/lib/protobuf/rpc/connectors/zmq.rb b/lib/protobuf/rpc/connectors/zmq.rb
index 3d99fb96..be517d61 100644
--- a/lib/protobuf/rpc/connectors/zmq.rb
+++ b/lib/protobuf/rpc/connectors/zmq.rb
@@ -2,6 +2,9 @@
 require "protobuf/rpc/connectors/base"
 require "protobuf/rpc/connectors/ping"
 require "protobuf/rpc/service_directory"
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Rpc
diff --git a/lib/protobuf/rpc/middleware.rb b/lib/protobuf/rpc/middleware.rb
index 3757b646..668f8830 100644
--- a/lib/protobuf/rpc/middleware.rb
+++ b/lib/protobuf/rpc/middleware.rb
@@ -21,5 +21,5 @@ def self.middleware
   Rpc.middleware.use(Rpc::Middleware::Logger)
   Rpc.middleware.use(Rpc::Middleware::ResponseEncoder)
 
-  ActiveSupport.run_load_hooks(:protobuf_rpc_middleware, Rpc)
+  ActiveSupport.run_load_hooks(:protobuf_rpc_middleware, Rpc) if Object.const_defined?('::ActiveSupport::LazyLoadHooks')
 end
diff --git a/lib/protobuf/rpc/middleware/logger.rb b/lib/protobuf/rpc/middleware/logger.rb
index 2c02b9a4..d833fa03 100644
--- a/lib/protobuf/rpc/middleware/logger.rb
+++ b/lib/protobuf/rpc/middleware/logger.rb
@@ -1,3 +1,7 @@
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Rpc
     module Middleware
diff --git a/lib/protobuf/rpc/middleware/request_decoder.rb b/lib/protobuf/rpc/middleware/request_decoder.rb
index c4efe823..5d8795ed 100644
--- a/lib/protobuf/rpc/middleware/request_decoder.rb
+++ b/lib/protobuf/rpc/middleware/request_decoder.rb
@@ -1,3 +1,9 @@
+require 'protobuf/refinements/string/constantize'
+require 'protobuf/refinements/string/underscore'
+
+using Protobuf::Refinements::String::Constantize
+using Protobuf::Refinements::String::Underscore
+
 module Protobuf
   module Rpc
     module Middleware
diff --git a/lib/protobuf/rpc/servers/socket_runner.rb b/lib/protobuf/rpc/servers/socket_runner.rb
index 8d36182d..b866c124 100644
--- a/lib/protobuf/rpc/servers/socket_runner.rb
+++ b/lib/protobuf/rpc/servers/socket_runner.rb
@@ -1,3 +1,7 @@
+require 'protobuf/refinements/hash/symbolize_keys'
+
+using Protobuf::Refinements::Hash::SymbolizeKeys
+
 module Protobuf
   module Rpc
     class SocketRunner
diff --git a/lib/protobuf/rpc/servers/zmq/broker.rb b/lib/protobuf/rpc/servers/zmq/broker.rb
index 2b12aee8..5f9e7278 100644
--- a/lib/protobuf/rpc/servers/zmq/broker.rb
+++ b/lib/protobuf/rpc/servers/zmq/broker.rb
@@ -1,4 +1,7 @@
 require 'thread'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Rpc
diff --git a/lib/protobuf/rpc/servers/zmq/server.rb b/lib/protobuf/rpc/servers/zmq/server.rb
index b5dce25a..fb45e928 100644
--- a/lib/protobuf/rpc/servers/zmq/server.rb
+++ b/lib/protobuf/rpc/servers/zmq/server.rb
@@ -1,3 +1,4 @@
+require 'protobuf/refinements/object/try'
 require 'protobuf/rpc/servers/zmq/util'
 require 'protobuf/rpc/servers/zmq/worker'
 require 'protobuf/rpc/servers/zmq/broker'
@@ -5,6 +6,8 @@
 require 'securerandom'
 require 'thread'
 
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Rpc
     module Zmq
diff --git a/lib/protobuf/rpc/servers/zmq/worker.rb b/lib/protobuf/rpc/servers/zmq/worker.rb
index 85e4aa2a..82d20479 100644
--- a/lib/protobuf/rpc/servers/zmq/worker.rb
+++ b/lib/protobuf/rpc/servers/zmq/worker.rb
@@ -1,7 +1,10 @@
+require 'protobuf/refinements/object/try'
 require 'protobuf/rpc/server'
 require 'protobuf/rpc/servers/zmq/util'
 require 'thread'
 
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Rpc
     module Zmq
diff --git a/lib/protobuf/rpc/servers/zmq_runner.rb b/lib/protobuf/rpc/servers/zmq_runner.rb
index bfab6738..1c392539 100644
--- a/lib/protobuf/rpc/servers/zmq_runner.rb
+++ b/lib/protobuf/rpc/servers/zmq_runner.rb
@@ -1,5 +1,10 @@
 require 'ostruct'
 require 'thread'
+require 'protobuf/refinements/hash/symbolize_keys'
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Hash::SymbolizeKeys
+using Protobuf::Refinements::Object::Try
 
 module Protobuf
   module Rpc
diff --git a/lib/protobuf/rpc/service.rb b/lib/protobuf/rpc/service.rb
index cc1974ad..142537e1 100644
--- a/lib/protobuf/rpc/service.rb
+++ b/lib/protobuf/rpc/service.rb
@@ -167,6 +167,6 @@ def rpc_failed(message)
       end
     end
 
-    ActiveSupport.run_load_hooks(:protobuf_rpc_service, Service)
+    ActiveSupport.run_load_hooks(:protobuf_rpc_service, Service) if Object.const_defined?('::ActiveSupport::LazyLoadHooks')
   end
 end
diff --git a/lib/protobuf/rpc/service_directory.rb b/lib/protobuf/rpc/service_directory.rb
index 7c467358..af1e812f 100644
--- a/lib/protobuf/rpc/service_directory.rb
+++ b/lib/protobuf/rpc/service_directory.rb
@@ -5,8 +5,11 @@
 require 'thread'
 require 'timeout'
 
+require 'protobuf/refinements/object/try'
 require 'protobuf/rpc/dynamic_discovery.pb'
 
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Rpc
     def self.service_directory
@@ -254,6 +257,7 @@ def run
       end
 
       def trigger(action, listing)
+        return unless Object.const_defined?('::ActiveSupport::Notifications')
         ::ActiveSupport::Notifications.instrument("directory.listing.#{action}", :listing => listing)
       end
     end
diff --git a/lib/protobuf/rpc/stat.rb b/lib/protobuf/rpc/stat.rb
index 841181a3..fe7dd127 100644
--- a/lib/protobuf/rpc/stat.rb
+++ b/lib/protobuf/rpc/stat.rb
@@ -1,8 +1,11 @@
 require 'date'
 require 'time'
 require 'protobuf/logging'
+require 'protobuf/refinements/object/try'
 require 'protobuf/rpc/rpc.pb'
 
+using Protobuf::Refinements::Object::Try
+
 module Protobuf
   module Rpc
     class Stat
diff --git a/protobuf-cucumber.gemspec b/protobuf-cucumber.gemspec
index a38aa0cd..020a3fc0 100644
--- a/protobuf-cucumber.gemspec
+++ b/protobuf-cucumber.gemspec
@@ -21,7 +21,8 @@ require "protobuf/version"
 
   # Hack, as Rails 5 requires Ruby version >= 2.2.2.
   active_support_max_version = "< 5" if Gem::Version.new(RUBY_VERSION) < Gem::Version.new("2.2.2")
-  s.add_dependency "activesupport", '>= 3.2', active_support_max_version
+  s.add_development_dependency "activesupport", '>= 3.2', active_support_max_version
+
   s.add_dependency 'middleware'
   s.add_dependency 'thor'
   s.add_dependency 'thread_safe'
diff --git a/spec/bin/protoc-gen-ruby_spec.rb b/spec/bin/protoc-gen-ruby_spec.rb
index 1df8b155..9991a8c5 100644
--- a/spec/bin/protoc-gen-ruby_spec.rb
+++ b/spec/bin/protoc-gen-ruby_spec.rb
@@ -17,7 +17,7 @@
       pipe.close_write # needed so we can implicitly read until EOF
       response_bytes = pipe.read
       response = ::Google::Protobuf::Compiler::CodeGeneratorResponse.decode(response_bytes)
-      expect(response.file.first.content).to include("module #{package.titleize}")
+      expect(response.file.first.content).to include("module Test")
     end
   end
 end
diff --git a/spec/lib/protobuf/cli_spec.rb b/spec/lib/protobuf/cli_spec.rb
index ea78ed0d..911a8f98 100644
--- a/spec/lib/protobuf/cli_spec.rb
+++ b/spec/lib/protobuf/cli_spec.rb
@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'active_support/notifications'
 require 'protobuf/cli'
 
 RSpec.describe ::Protobuf::CLI do
diff --git a/spec/lib/protobuf/enum_spec.rb b/spec/lib/protobuf/enum_spec.rb
index f0ace1d6..511acb1c 100644
--- a/spec/lib/protobuf/enum_spec.rb
+++ b/spec/lib/protobuf/enum_spec.rb
@@ -1,6 +1,10 @@
 require 'spec_helper'
 require PROTOS_PATH.join('enum.pb')
 
+require 'protobuf/refinements/object/try'
+
+using Protobuf::Refinements::Object::Try
+
 RSpec.describe Protobuf::Enum do
 
   describe 'class dsl' do
diff --git a/spec/lib/protobuf/lifecycle_spec.rb b/spec/lib/protobuf/lifecycle_spec.rb
index d1414477..d48d3020 100644
--- a/spec/lib/protobuf/lifecycle_spec.rb
+++ b/spec/lib/protobuf/lifecycle_spec.rb
@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'active_support/notifications'
 require 'protobuf/lifecycle'
 
 RSpec.describe ::Protobuf::Lifecycle do
diff --git a/spec/lib/protobuf/message_spec.rb b/spec/lib/protobuf/message_spec.rb
index 6a3f6d9c..47fe9890 100644
--- a/spec/lib/protobuf/message_spec.rb
+++ b/spec/lib/protobuf/message_spec.rb
@@ -5,6 +5,10 @@
 require PROTOS_PATH.join('resource.pb')
 require PROTOS_PATH.join('enum.pb')
 
+require 'protobuf/refinements/kernel/blank'
+
+using Protobuf::Refinements::Kernel::Blank
+
 RSpec.describe Protobuf::Message do
 
   describe '.decode' do
diff --git a/spec/lib/protobuf/rpc/service_directory_spec.rb b/spec/lib/protobuf/rpc/service_directory_spec.rb
index 268bb021..05cfefcb 100644
--- a/spec/lib/protobuf/rpc/service_directory_spec.rb
+++ b/spec/lib/protobuf/rpc/service_directory_spec.rb
@@ -1,5 +1,6 @@
 require 'spec_helper'
 
+require 'active_support/notifications'
 require 'protobuf/rpc/service_directory'
 
 RSpec.describe ::Protobuf::Rpc::ServiceDirectory do
diff --git a/spec/lib/protobuf/rpc/stat_spec.rb b/spec/lib/protobuf/rpc/stat_spec.rb
index 9abd627f..e629914b 100644
--- a/spec/lib/protobuf/rpc/stat_spec.rb
+++ b/spec/lib/protobuf/rpc/stat_spec.rb
@@ -1,6 +1,5 @@
 require 'spec_helper'
 require 'timecop'
-require 'active_support/core_ext/numeric/time'
 
 RSpec.describe ::Protobuf::Rpc::Stat do
 
@@ -24,14 +23,14 @@
 
   describe 'server mode' do
     it 'describes a server response to a client' do
-      ::Timecop.freeze(10.minutes.ago) do
+      ::Timecop.freeze(Time.now - 10 * 60) do
         stats = ::Protobuf::Rpc::Stat.new(:SERVER)
         stats.client = 'myserver1'
         stats.dispatcher = double('dispatcher', :service => BarService.new(:find_bars))
         stats.request_size = 43
         stats.response_size = 1302
 
-        ::Timecop.freeze(1.62.seconds.from_now) do
+        ::Timecop.freeze(Time.now + 1.62) do
           stats.stop
           expect(stats.to_s).to eq "[SRV] - myserver1 - #{stats.trace_id} - BarService#find_bars - 43B/1302B - 1.62s - OK - #{::Time.now.iso8601}"
         end
@@ -51,7 +50,7 @@
 
   describe 'client mode' do
     it 'describes a client request to a server' do
-      ::Timecop.freeze(10.minutes.ago) do
+      ::Timecop.freeze(Time.now - 10 * 60) do
         stats = ::Protobuf::Rpc::Stat.new(:CLIENT)
         stats.server = ['30000', 'myserver1.myhost.com']
         stats.service = 'Foo::BarService'
@@ -59,7 +58,7 @@
         stats.request_size = 37
         stats.response_size = 12345
 
-        ::Timecop.freeze(0.832.seconds.from_now) do
+        ::Timecop.freeze(Time.now + 0.832) do
           stats.stop
           expect(stats.to_s).to eq "[CLT] - myserver1.myhost.com:30000 - #{stats.trace_id} - Foo::BarService#find_bars - 37B/12345B - 0.832s - OK - #{::Time.now.iso8601}"
         end
@@ -69,7 +68,7 @@
 
     describe 'error log' do
       it 'resolves error to a string' do
-        ::Timecop.freeze(10.minutes.ago) do
+        ::Timecop.freeze(Time.now - 10 * 60) do
           stats = ::Protobuf::Rpc::Stat.new(:CLIENT)
           stats.server = ['30000', 'myserver1.myhost.com']
           stats.service = 'Foo::BarService'
@@ -78,7 +77,7 @@
           stats.request_size = 37
           stats.response_size = 12345
 
-          ::Timecop.freeze(0.832.seconds.from_now) do
+          ::Timecop.freeze(Time.now + 0.832) do
             stats.stop
             expect(stats.to_s).to eq "[CLT] - myserver1.myhost.com:30000 - #{stats.trace_id} - Foo::BarService#find_bars - 37B/12345B - 0.832s - RPC_ERROR - #{::Time.now.iso8601}"
           end
diff --git a/spec/support/packed_field.rb b/spec/support/packed_field.rb
index 9b18efee..aba61357 100644
--- a/spec/support/packed_field.rb
+++ b/spec/support/packed_field.rb
@@ -1,3 +1,7 @@
+require 'protobuf/refinements/string/underscore'
+
+using Protobuf::Refinements::String::Underscore
+
 if defined?(RSpec)
   shared_examples_for :packable_field do |field_klass|
 
diff --git a/spec/support/server.rb b/spec/support/server.rb
index 8a0203b6..9c5b7635 100644
--- a/spec/support/server.rb
+++ b/spec/support/server.rb
@@ -1,7 +1,5 @@
 require 'ostruct'
 
-require 'active_support/core_ext/hash/reverse_merge'
-
 require 'spec_helper'
 require 'protobuf/logging'
 require 'protobuf/rpc/server'
@@ -25,13 +23,13 @@ class StubServer
 
   def initialize(options = {})
     self.options = OpenStruct.new(
-      options.reverse_merge(
+      {
         :host => '127.0.0.1',
         :port => 9399,
         :worker_port => 9400,
         :delay => 0,
         :server => Protobuf::Rpc::Socket::Server,
-      ),
+      }.merge(options),
     )
 
     start