diff --git a/build_tests/custom_builder/Rsconscript b/build_tests/custom_builder/Rsconscript
index 01f83a7..d38a962 100644
--- a/build_tests/custom_builder/Rsconscript
+++ b/build_tests/custom_builder/Rsconscript
@@ -11,7 +11,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(MySource.new)
+    env.add_builder(MySource)
     env.MySource('inc.h', [])
     env.Program('program.exe', Dir['*.c'])
   end
diff --git a/build_tests/custom_builder/cvar_expansion.rb b/build_tests/custom_builder/cvar_expansion.rb
index 9bc26e6..d4a80f3 100644
--- a/build_tests/custom_builder/cvar_expansion.rb
+++ b/build_tests/custom_builder/cvar_expansion.rb
@@ -13,7 +13,7 @@ build do
   env = Environment.new do |env|
     env["hdr"] = "inc.h"
     env["src"] = "program.c"
-    env.add_builder(MySource.new)
+    env.add_builder(MySource)
     env.MySource('${hdr}')
     env.Program('program.exe', "${src}")
   end
diff --git a/build_tests/custom_builder/cvar_lambda.rb b/build_tests/custom_builder/cvar_lambda.rb
index adeba08..90b8b30 100644
--- a/build_tests/custom_builder/cvar_lambda.rb
+++ b/build_tests/custom_builder/cvar_lambda.rb
@@ -11,7 +11,7 @@ end
 
 build do
   e1 = Environment.new do |env|
-    env.add_builder(MySource.new)
+    env.add_builder(MySource)
     env["one"] = "5"
     env[:cfg] = {val: "9"}
     env["two"] = lambda do |args|
diff --git a/build_tests/custom_builder/multiple_targets.rb b/build_tests/custom_builder/multiple_targets.rb
index 4adf364..a1d9abc 100644
--- a/build_tests/custom_builder/multiple_targets.rb
+++ b/build_tests/custom_builder/multiple_targets.rb
@@ -14,7 +14,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(CHGen.new)
+    env.add_builder(CHGen)
     env.CHGen("inc.c", ["program.c"])
     env.Program("program.exe", %w[program.c inc.c])
   end
diff --git a/build_tests/json_to_yaml/Rsconscript b/build_tests/json_to_yaml/Rsconscript
index 4ba0a4f..a5177ab 100644
--- a/build_tests/json_to_yaml/Rsconscript
+++ b/build_tests/json_to_yaml/Rsconscript
@@ -2,7 +2,8 @@ build do
   Environment.new do |env|
     require 'json'
     require 'yaml'
-    env.add_builder(:JsonToYaml) do |target, sources, cache, env, vars|
+    env.add_builder(:JsonToYaml) do |params|
+      target, sources, cache, env, vars = params.values_at(:target, :sources, :cache, :env, :vars)
       unless cache.up_to_date?(target, :JsonToYaml, sources, env)
         cache.mkdir_p(File.dirname(target))
         File.open(target, 'w') do |f|
diff --git a/build_tests/simple/builder_no_sources.rb b/build_tests/simple/builder_no_sources.rb
index f067642..a50602d 100644
--- a/build_tests/simple/builder_no_sources.rb
+++ b/build_tests/simple/builder_no_sources.rb
@@ -5,7 +5,7 @@ class TestBuilder < Rscons::Builder
 end
 build do
   Environment.new do |env|
-    env.add_builder(TestBuilder.new)
+    env.add_builder(TestBuilder)
     env.TestBuilder("file")
   end
 end
diff --git a/build_tests/simple/cache_debugging.rb b/build_tests/simple/cache_debugging.rb
index 6fcdd3a..bc58029 100644
--- a/build_tests/simple/cache_debugging.rb
+++ b/build_tests/simple/cache_debugging.rb
@@ -30,7 +30,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(DebugBuilder.new)
+    env.add_builder(DebugBuilder)
     if Rscons.vars["new_user_dep"]
       env.depends("foo.o", "new_dep")
     end
diff --git a/build_tests/simple/cache_varset.rb b/build_tests/simple/cache_varset.rb
index a0ebe12..0c8e34e 100644
--- a/build_tests/simple/cache_varset.rb
+++ b/build_tests/simple/cache_varset.rb
@@ -16,7 +16,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(TestBuilder.new)
+    env.add_builder(TestBuilder)
     env.TestBuilder("foo")
   end
 end
diff --git a/build_tests/simple/phony_target.rb b/build_tests/simple/phony_target.rb
index 665661d..8ee5071 100644
--- a/build_tests/simple/phony_target.rb
+++ b/build_tests/simple/phony_target.rb
@@ -1,6 +1,7 @@
 build do
   Environment.new do |env|
-    env.add_builder(:Checker) do |target, sources, cache, env, vars|
+    env.add_builder(:Checker) do |params|
+      target, sources, cache, env, vars = params.values_at(:target, :sources, :cache, :env, :vars)
       unless cache.up_to_date?(target, :Checker, sources, env)
         puts "Checker #{sources.first}" if env.echo != :off
         cache.register_build(target, :Checker, sources, env)
diff --git a/build_tests/simple/run_builder.rb b/build_tests/simple/run_builder.rb
index 1f56fbc..18e4b77 100644
--- a/build_tests/simple/run_builder.rb
+++ b/build_tests/simple/run_builder.rb
@@ -1,13 +1,13 @@
 class MyObject < Rscons::Builder
   def run(options)
     target, sources, cache, env, vars = options.values_at(:target, :sources, :cache, :env, :vars)
-    env.run_builder(env.builders["Object"], target, sources, cache, vars)
+    env.run_builder(env.builders["Object"].new, target, sources, cache, vars)
   end
 end
 
 build do
   Environment.new do |env|
-    env.add_builder(MyObject.new)
+    env.add_builder(MyObject)
     env.MyObject("simple.o", "simple.c")
     env.Program("simple.exe", "simple.o")
   end
diff --git a/build_tests/simple/threading.rb b/build_tests/simple/threading.rb
index b6768e1..c216c85 100644
--- a/build_tests/simple/threading.rb
+++ b/build_tests/simple/threading.rb
@@ -20,8 +20,8 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(ThreadedTestBuilder.new)
-    env.add_builder(NonThreadedTestBuilder.new)
+    env.add_builder(ThreadedTestBuilder)
+    env.add_builder(NonThreadedTestBuilder)
     env.ThreadedTestBuilder("a")
     env.ThreadedTestBuilder("b")
     env.ThreadedTestBuilder("c")
diff --git a/build_tests/simple/user_dep_build_order.rb b/build_tests/simple/user_dep_build_order.rb
index a24cced..2243f8f 100644
--- a/build_tests/simple/user_dep_build_order.rb
+++ b/build_tests/simple/user_dep_build_order.rb
@@ -16,7 +16,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(TestBuilder.new)
+    env.add_builder(TestBuilder)
     env.TestBuilder("one", [], "wait_time" => "3")
     env.TestBuilder("two", [], "wait_time" => "0")
     env.depends("two", "one")
diff --git a/build_tests/simple/wait_for_builds_on_failure.rb b/build_tests/simple/wait_for_builds_on_failure.rb
index b7ee54d..04b7867 100644
--- a/build_tests/simple/wait_for_builds_on_failure.rb
+++ b/build_tests/simple/wait_for_builds_on_failure.rb
@@ -13,7 +13,7 @@ end
 
 build do
   Environment.new do |env|
-    env.add_builder(Fail.new)
+    env.add_builder(Fail)
     4.times do |i|
       wait_time = i + 1
       env.Fail("foo_#{wait_time}", [], "wait_time" => wait_time.to_s)
diff --git a/build_tests/two_sources/cache_strict_deps.rb b/build_tests/two_sources/cache_strict_deps.rb
index df8c4ff..47a631b 100644
--- a/build_tests/two_sources/cache_strict_deps.rb
+++ b/build_tests/two_sources/cache_strict_deps.rb
@@ -16,7 +16,7 @@ end
 
 build do
   Environment.new(echo: :command) do |env|
-    env.add_builder(StrictBuilder.new)
+    env.add_builder(StrictBuilder)
     env.Object("one.o", "one.c", "CCFLAGS" => %w[-DONE])
     env.Object("two.o", "two.c")
     sources = File.read("sources", mode: "rb").split(" ")
diff --git a/build_tests/typical/backward_compatible_build_hooks.rb b/build_tests/typical/backward_compatible_build_hooks.rb
index 270363a..9e63d37 100644
--- a/build_tests/typical/backward_compatible_build_hooks.rb
+++ b/build_tests/typical/backward_compatible_build_hooks.rb
@@ -1,12 +1,12 @@
 class MyObject < Rscons::Builder
   def run(target, sources, cache, env, vars)
-    env.run_builder(env.builders["Object"], target, sources, cache, vars)
+    env.run_builder(env.builders["Object"].new, target, sources, cache, vars)
   end
 end
 
 build do
   Environment.new(echo: :command) do |env|
-    env.add_builder(MyObject.new)
+    env.add_builder(MyObject)
     env.append('CPPPATH' => Rscons.glob('src/**'))
     env.add_build_hook do |build_op|
       if build_op[:builder].name == "MyObject" && build_op[:sources].first =~ %r{one\.c}
diff --git a/build_tests/typical/echo_command_string.rb b/build_tests/typical/echo_command_string.rb
index 4b0be44..f54bc18 100644
--- a/build_tests/typical/echo_command_string.rb
+++ b/build_tests/typical/echo_command_string.rb
@@ -9,7 +9,7 @@ end
 build do
   Environment.new do |env|
     env.echo = :command
-    env.add_builder(MyBuilder.new)
+    env.add_builder(MyBuilder)
     env.MyBuilder("foo")
   end
 end
diff --git a/lib/rscons.rb b/lib/rscons.rb
index 7d1ab44..48d38d2 100644
--- a/lib/rscons.rb
+++ b/lib/rscons.rb
@@ -3,6 +3,7 @@ require_relative "rscons/application"
 require_relative "rscons/basic_environment"
 require_relative "rscons/build_target"
 require_relative "rscons/builder"
+require_relative "rscons/builder_builder"
 require_relative "rscons/cache"
 require_relative "rscons/configure_op"
 require_relative "rscons/environment"
diff --git a/lib/rscons/builder.rb b/lib/rscons/builder.rb
index d40b970..ebb0465 100644
--- a/lib/rscons/builder.rb
+++ b/lib/rscons/builder.rb
@@ -6,21 +6,49 @@ module Rscons
 
   # Class to hold an object that knows how to build a certain type of file.
   class Builder
+    class << self
+      # Return the name of the builder.
+      #
+      # If not overridden this defaults to the last component of the class name.
+      #
+      # @return [String] The name of the builder.
+      def name
+        super.split(":").last
+      end
+
+      # Return a set of build features that this builder provides.
+      #
+      # @return [Array<String>]
+      #   Set of build features that this builder provides.
+      def features
+        []
+      end
+
+      # Return whether this builder object is capable of producing a given target
+      # file name from a given source file name.
+      #
+      # @param target [String]
+      #   The target file name.
+      # @param source [String]
+      #   The source file name.
+      # @param env [Environment]
+      #   The Environment.
+      #
+      # @return [Boolean]
+      #   Whether this builder object is capable of producing a given target
+      #   file name from a given source file name.
+      def produces?(target, source, env)
+        false
+      end
+    end
+
     # Return the name of the builder.
     #
     # If not overridden this defaults to the last component of the class name.
     #
     # @return [String] The name of the builder.
     def name
-      self.class.name.split(":").last
-    end
-
-    # Return a set of build features that this builder provides.
-    #
-    # @return [Array<String>]
-    #   Set of build features that this builder provides.
-    def features
-      []
+      self.class.name
     end
 
     # Create a BuildTarget object for this build target.
@@ -43,23 +71,6 @@ module Rscons
       BuildTarget.new(options)
     end
 
-    # Return whether this builder object is capable of producing a given target
-    # file name from a given source file name.
-    #
-    # @param target [String]
-    #   The target file name.
-    # @param source [String]
-    #   The source file name.
-    # @param env [Environment]
-    #   The Environment.
-    #
-    # @return [Boolean]
-    #   Whether this builder object is capable of producing a given target
-    #   file name from a given source file name.
-    def produces?(target, source, env)
-      false
-    end
-
     # Set up a build operation using this builder.
     #
     # This method is called when a build target is registered using this
diff --git a/lib/rscons/builder_builder.rb b/lib/rscons/builder_builder.rb
new file mode 100644
index 0000000..67e2ed8
--- /dev/null
+++ b/lib/rscons/builder_builder.rb
@@ -0,0 +1,33 @@
+module Rscons
+  # A class that knows how to build an instance of another Builder class when
+  # it is needed.
+  class BuilderBuilder
+
+    # @return [String] Builder name.
+    attr_reader :name
+
+    # Create a BuilderBuilder.
+    #
+    # @param name [String]
+    #   Builder name.
+    # @param builder_class [Class]
+    #   The {Builder} class to be instantiated.
+    # @param builder_args [Array]
+    #   Any extra arguments to be passed to the builder class.
+    # @param builder_block [Proc, nil]
+    #   Optional block to be passed to the {Builder} class's #new method.
+    def initialize(name, builder_class, *builder_args, &builder_block)
+      @name = name
+      @builder_class = builder_class
+      @builder_args = builder_args
+      @builder_block = builder_block
+    end
+
+    # Act like a regular {Builder} class object but really instantiate the
+    # requested {Builder} class, potentially with extra arguments and a block.
+    def new(*args)
+      @builder_class.new(*args, *@builder_args, &@builder_block)
+    end
+
+  end
+end
diff --git a/lib/rscons/builders/install.rb b/lib/rscons/builders/install.rb
index 7756093..036570b 100644
--- a/lib/rscons/builders/install.rb
+++ b/lib/rscons/builders/install.rb
@@ -43,7 +43,7 @@ module Rscons
           # Check the cache and copy if necessary
           unless cache.up_to_date?(dest, :Copy, [src], env)
             unless printed_message
-              env.print_builder_run_message("#{name} #{target}", nil)
+              env.print_builder_run_message("#{self.class.name} #{target}", nil)
               printed_message = true
             end
             cache.mkdir_p(File.dirname(dest))
diff --git a/lib/rscons/builders/object.rb b/lib/rscons/builders/object.rb
index f6ca90e..6bf807f 100644
--- a/lib/rscons/builders/object.rb
+++ b/lib/rscons/builders/object.rb
@@ -53,24 +53,26 @@ module Rscons
         'DCCMD' => ['${DC}', '-c', '-o', '${_TARGET}', '${DDEPGEN}', '${INCPREFIX}${D_IMPORT_PATH}', '${DFLAGS}', '${_SOURCES}'],
       )
 
-      # Return whether this builder object is capable of producing a given target
-      # file name from a given source file name.
-      #
-      # @param target [String]
-      #   The target file name.
-      # @param source [String]
-      #   The source file name.
-      # @param env [Environment]
-      #   The Environment.
-      #
-      # @return [Boolean]
-      #   Whether this builder object is capable of producing a given target
-      #   file name from a given source file name.
-      def produces?(target, source, env)
-        target.end_with?(*env['OBJSUFFIX']) and
-          KNOWN_SUFFIXES.find do |compiler, suffix_var|
-            source.end_with?(*env[suffix_var])
-          end
+      class << self
+        # Return whether this builder object is capable of producing a given target
+        # file name from a given source file name.
+        #
+        # @param target [String]
+        #   The target file name.
+        # @param source [String]
+        #   The source file name.
+        # @param env [Environment]
+        #   The Environment.
+        #
+        # @return [Boolean]
+        #   Whether this builder object is capable of producing a given target
+        #   file name from a given source file name.
+        def produces?(target, source, env)
+          target.end_with?(*env['OBJSUFFIX']) and
+            KNOWN_SUFFIXES.find do |compiler, suffix_var|
+              source.end_with?(*env[suffix_var])
+            end
+        end
       end
 
       # Run the builder to produce a build target.
diff --git a/lib/rscons/builders/preprocess.rb b/lib/rscons/builders/preprocess.rb
index f3fd943..2238cc5 100644
--- a/lib/rscons/builders/preprocess.rb
+++ b/lib/rscons/builders/preprocess.rb
@@ -36,7 +36,7 @@ module Rscons
         env.produces(target, vars['_DEPFILE'])
         # Store vars back into options so new keys are accessible in #finalize.
         options[:vars] = vars
-        standard_threaded_build("#{name} #{target}", target, command, sources, env, cache)
+        standard_threaded_build("#{self.class.name} #{target}", target, command, sources, env, cache)
       end
 
       # Finalize the build operation.
diff --git a/lib/rscons/builders/shared_library.rb b/lib/rscons/builders/shared_library.rb
index a7912a3..5020647 100644
--- a/lib/rscons/builders/shared_library.rb
+++ b/lib/rscons/builders/shared_library.rb
@@ -14,12 +14,14 @@ module Rscons
         'SHLDCMD' => ['${SHLD}', '-o', '${_TARGET}', '${SHLDFLAGS}', '${_SOURCES}', '${SHLIBDIRPREFIX}${LIBPATH}', '${SHLIBLINKPREFIX}${LIBS}']
       )
 
-      # Return a set of build features that this builder provides.
-      #
-      # @return [Array<String>]
-      #   Set of build features that this builder provides.
-      def features
-        %w[shared]
+      class << self
+        # Return a set of build features that this builder provides.
+        #
+        # @return [Array<String>]
+        #   Set of build features that this builder provides.
+        def features
+          %w[shared]
+        end
       end
 
       # Create a BuildTarget object for this build target.
diff --git a/lib/rscons/builders/shared_object.rb b/lib/rscons/builders/shared_object.rb
index 8c864ee..34bb522 100644
--- a/lib/rscons/builders/shared_object.rb
+++ b/lib/rscons/builders/shared_object.rb
@@ -30,32 +30,34 @@ module Rscons
         'SHDCCMD' => ['${SHDC}', '-c', '-o', '${_TARGET}', '${INCPREFIX}${D_IMPORT_PATH}', '${SHDFLAGS}', '${_SOURCES}'],
       )
 
-      # Return a set of build features that this builder provides.
-      #
-      # @return [Array<String>]
-      #   Set of build features that this builder provides.
-      def features
-        %w[shared]
-      end
+      class << self
+        # Return a set of build features that this builder provides.
+        #
+        # @return [Array<String>]
+        #   Set of build features that this builder provides.
+        def features
+          %w[shared]
+        end
 
-      # Return whether this builder object is capable of producing a given target
-      # file name from a given source file name.
-      #
-      # @param target [String]
-      #   The target file name.
-      # @param source [String]
-      #   The source file name.
-      # @param env [Environment]
-      #   The Environment.
-      #
-      # @return [Boolean]
-      #   Whether this builder object is capable of producing a given target
-      #   file name from a given source file name.
-      def produces?(target, source, env)
-        target.end_with?(*env['OBJSUFFIX']) and
-          KNOWN_SUFFIXES.find do |compiler, suffix_var|
-            source.end_with?(*env[suffix_var])
-          end
+        # Return whether this builder object is capable of producing a given target
+        # file name from a given source file name.
+        #
+        # @param target [String]
+        #   The target file name.
+        # @param source [String]
+        #   The source file name.
+        # @param env [Environment]
+        #   The Environment.
+        #
+        # @return [Boolean]
+        #   Whether this builder object is capable of producing a given target
+        #   file name from a given source file name.
+        def produces?(target, source, env)
+          target.end_with?(*env['OBJSUFFIX']) and
+            KNOWN_SUFFIXES.find do |compiler, suffix_var|
+              source.end_with?(*env[suffix_var])
+            end
+        end
       end
 
       # Run the builder to produce a build target.
diff --git a/lib/rscons/builders/simple_builder.rb b/lib/rscons/builders/simple_builder.rb
index ae21f05..512d151 100644
--- a/lib/rscons/builders/simple_builder.rb
+++ b/lib/rscons/builders/simple_builder.rb
@@ -1,39 +1,26 @@
 module Rscons
   module Builders
-    # A Generic builder class whose name and operation is defined at
-    # instantiation.
+    # A Generic builder which has its operation is defined at instantiation.
     #
     # @since 1.8.0
     class SimpleBuilder < Builder
-      # @return [String] The name of this builder.
-      attr_reader :name
 
-      # Create a new builder with the given name and action.
+      # Create a new builder with the given action.
       #
-      # @param name  [String,Symbol] The name of the builder when registered.
-      # @param block [Block]
-      #   The action to perform when the builder is processed. The provided
-      #   block must return the target file on success or false on failure.
-      #   The provided block should have the same signature as {Builder#run}.
-      def initialize(name, &block)
-        @name  = name.to_s
-        @block = block
+      # @param run_proc [Proc]
+      #   A Proc to execute when the builder runs. The provided block must
+      #   provide the have the same signature as {Builder#run}.
+      def initialize(&run_proc)
+        @run_proc = run_proc
       end
 
       # Run the builder to produce a build target.
       #
-      # @param target [String] Target file name.
-      # @param sources [Array<String>] Source file name(s).
-      # @param cache [Cache] The Cache object.
-      # @param env [Environment] The Environment executing the builder.
-      # @param vars [Hash,VarSet] Extra construction variables.
-      #
-      # @return [String,false]
-      #   Name of the target file on success or false on failure.
-      def run(target, sources, cache, env, vars)
-        @block.call(target, sources, cache, env, vars)
+      # Method signature described by {Builder#run}.
+      def run(*args)
+        @run_proc.call(*args)
       end
+
     end
   end
 end
-
diff --git a/lib/rscons/environment.rb b/lib/rscons/environment.rb
index 9e3cb20..12a822a 100644
--- a/lib/rscons/environment.rb
+++ b/lib/rscons/environment.rb
@@ -72,13 +72,14 @@ module Rscons
       @side_effects = {}
       @job_set = JobSet.new(@registered_build_dependencies, @side_effects)
       @user_deps = {}
+      # Hash of builder name (String) => builder class (Class).
       @builders = {}
       @build_hooks = {pre: [], post: []}
       unless options[:exclude_builders]
         DEFAULT_BUILDERS.each do |builder_class_name|
           builder_class = Builders.const_get(builder_class_name)
           builder_class or raise "Could not find builder class #{builder_class_name}"
-          add_builder(builder_class.new)
+          add_builder(builder_class)
         end
       end
       @echo =
@@ -146,22 +147,22 @@ module Rscons
       env
     end
 
-    # Add a {Builder} object to the Environment.
+    # Add a {Builder} to the Environment.
     #
-    # @overload add_builder(builder)
+    # @overload add_builder(builder_class)
     #
     #   Add the given builder to the Environment.
     #
-    #   @param builder [Builder] An instance of the builder to register.
+    #   @param builder_class [Class] A builder class to register.
     #
-    # @overload add_builder(builder,&action)
+    # @overload add_builder(name,&action)
     #
     #   Create a new {Builders::SimpleBuilder} instance and add it to the
     #   environment.
     #
     #   @since 1.8.0
     #
-    #   @param builder [String,Symbol]
+    #   @param name [String,Symbol]
     #     The name of the builder to add.
     #
     #   @param action [Block]
@@ -170,11 +171,11 @@ module Rscons
     #     {Rscons::Builder#run}.
     #
     # @return [void]
-    def add_builder(builder, &action)
-      if not builder.is_a? Rscons::Builder
-        builder = Rscons::Builders::SimpleBuilder.new(builder, &action)
+    def add_builder(builder_class, &action)
+      if builder_class.is_a?(String) or builder_class.is_a?(Symbol)
+        builder_class = BuilderBuilder.new(builder_class.to_s, Rscons::Builders::SimpleBuilder, &action)
       end
-      @builders[builder.name] = builder
+      @builders[builder_class.name] = builder_class
     end
 
     # Add a build hook to the Environment.
@@ -351,7 +352,7 @@ module Rscons
         unless vars.is_a?(Hash) or vars.is_a?(VarSet)
           raise "Unexpected construction variable set: #{vars.inspect}"
         end
-        builder = @builders[method.to_s]
+        builder = @builders[method.to_s].new
         target = expand_path(expand_varref(target))
         sources = Array(sources).map do |source|
           expand_path(expand_varref(source))
@@ -789,22 +790,22 @@ module Rscons
     # @return [Builder, nil]
     #   The builder found, if any.
     def find_builder_for(target, source, features)
-      @builders.values.find do |builder|
-        features_met?(builder, features) and builder.produces?(target, source, self)
+      @builders.values.find do |builder_class|
+        features_met?(builder_class, features) and builder_class.produces?(target, source, self)
       end
     end
 
     # Determine if a builder meets the requested features.
     #
-    # @param builder [Builder]
+    # @param builder_class [Class]
     #   The builder.
     # @param features [Array<String>]
     #   See {#register_builds}.
     #
     # @return [Boolean]
     #   Whether the builder meets the requested features.
-    def features_met?(builder, features)
-      builder_features = builder.features
+    def features_met?(builder_class, features)
+      builder_features = builder_class.features
       features.all? do |feature|
         want_feature = true
         if feature =~ /^-(.*)$/
diff --git a/spec/rscons/builders/simple_builder_spec.rb b/spec/rscons/builders/simple_builder_spec.rb
index 0031221..569a2fe 100644
--- a/spec/rscons/builders/simple_builder_spec.rb
+++ b/spec/rscons/builders/simple_builder_spec.rb
@@ -3,15 +3,8 @@ module Rscons
     describe SimpleBuilder do
       let(:env) {Environment.new}
 
-      it "should create a new builder with the given name (as a symbol) and action" do
-        builder = Rscons::Builders::SimpleBuilder.new(:Foo) { 0x1234 }
-        expect(builder.name).to eq("Foo")
-        expect(builder.run(1,2,3,4,5)).to eq(0x1234)
-      end
-
-      it "should create a new builder with the given name (as a string) and action" do
-        builder = Rscons::Builders::SimpleBuilder.new("Foo") { 0x1234 }
-        expect(builder.name).to eq("Foo")
+      it "should create a new builder with the given action" do
+        builder = Rscons::Builders::SimpleBuilder.new { 0x1234 }
         expect(builder.run(1,2,3,4,5)).to eq(0x1234)
       end
     end
diff --git a/spec/rscons/environment_spec.rb b/spec/rscons/environment_spec.rb
index f3459e4..351dc9b 100644
--- a/spec/rscons/environment_spec.rb
+++ b/spec/rscons/environment_spec.rb
@@ -4,7 +4,7 @@ module Rscons
       it "adds the default builders when they are not excluded" do
         env = Environment.new
         expect(env.builders.size).to be > 0
-        expect(env.builders.map {|name, builder| builder.is_a?(Builder)}.all?).to be_truthy
+        expect(env.builders.map {|name, builder| builder.is_a?(Class)}.all?).to be_truthy
         expect(env.builders.find {|name, builder| name == "Object"}).to_not be_nil
         expect(env.builders.find {|name, builder| name == "Program"}).to_not be_nil
         expect(env.builders.find {|name, builder| name == "Library"}).to_not be_nil
@@ -52,7 +52,7 @@ module Rscons
       it "adds the builder to the list of builders" do
         env = Environment.new(exclude_builders: true)
         expect(env.builders.keys).to eq []
-        env.add_builder(Rscons::Builders::Object.new)
+        env.add_builder(Rscons::Builders::Object)
         expect(env.builders.keys).to eq ["Object"]
       end