diff --git a/lib/rscons.rb b/lib/rscons.rb
index dddf970..6027d48 100644
--- a/lib/rscons.rb
+++ b/lib/rscons.rb
@@ -3,10 +3,10 @@ require_relative "rscons/application"
 require_relative "rscons/basic_environment"
 require_relative "rscons/builder"
 require_relative "rscons/builder_builder"
+require_relative "rscons/builder_set"
 require_relative "rscons/cache"
 require_relative "rscons/configure_op"
 require_relative "rscons/environment"
-require_relative "rscons/job_set"
 require_relative "rscons/script"
 require_relative "rscons/threaded_command"
 require_relative "rscons/util"
diff --git a/lib/rscons/builder_set.rb b/lib/rscons/builder_set.rb
new file mode 100644
index 0000000..2d79255
--- /dev/null
+++ b/lib/rscons/builder_set.rb
@@ -0,0 +1,75 @@
+module Rscons
+  # Class to keep track of a set of builders to be executed.
+  class BuilderSet < Hash
+
+    # Create a BuilderSet.
+    #
+    # @param build_dependencies [Hash]
+    #   Hash mapping targets to a set of build dependencies. A builder will not
+    #   be returned as ready to run if any of its dependencies are still
+    #   building.
+    # @param side_effects [Hash]
+    #   Hash mapping targets to a set of side-effect files. A builder will not
+    #   be returned as ready to run if any of its dependencies is a side-effect
+    #   of another target that has not yet been built.
+    def initialize(build_dependencies, side_effects)
+      super()
+      @build_dependencies = build_dependencies
+      @side_effects = side_effects
+    end
+
+    # Add a builder to the BuilderSet.
+    #
+    # @param builder [Builder]
+    #   The {Builder} that will produce the target.
+    def <<(builder)
+      # We allow multiple builders to be registered per target for cases like:
+      #   env.Directory("dest")
+      #   env.Install("dest", "bin")
+      #   env.Install("dest", "share")
+      self[builder.target] ||= []
+      self[builder.target] << builder
+    end
+
+    # Get the next builder that is ready to run from the BuilderSet.
+    #
+    # This method will remove the builder from the BuilderSet.
+    #
+    # @param targets_still_building [Array<String>]
+    #   Targets that are not finished building. This is used to avoid returning
+    #   a builder as available to run if it depends on one of the targets that
+    #   are still building as a source.
+    #
+    # @return [nil, Builder]
+    #   The next builder to run.
+    def get_next_builder_to_run(targets_still_building)
+      not_built_yet = targets_still_building + self.keys
+      not_built_yet += not_built_yet.reduce([]) do |result, target|
+        result + (@side_effects[target] || [])
+      end
+
+      target_to_build = self.keys.find do |target|
+        deps = self[target][0].sources + (@build_dependencies[target] || []).to_a
+        !deps.find {|dep| not_built_yet.include?(dep)}
+      end
+
+      if target_to_build
+        builder = self[target_to_build][0]
+        if self[target_to_build].size > 1
+          self[target_to_build].slice!(0)
+        else
+          self.delete(target_to_build)
+        end
+        return builder
+      end
+
+      # If there is a builder to run, and nothing is still building, but we did
+      # not find a builder to run above, then there might be a circular
+      # dependency introduced by the user.
+      if (self.size > 0) and targets_still_building.empty?
+        raise "Could not find a runnable builder. Possible circular dependency for #{self.keys.first}"
+      end
+    end
+
+  end
+end
diff --git a/lib/rscons/environment.rb b/lib/rscons/environment.rb
index ac24b64..4209ea9 100644
--- a/lib/rscons/environment.rb
+++ b/lib/rscons/environment.rb
@@ -70,7 +70,7 @@ module Rscons
       @threaded_commands = Set.new
       @registered_build_dependencies = {}
       @side_effects = {}
-      @job_set = JobSet.new(@registered_build_dependencies, @side_effects)
+      @builder_set = BuilderSet.new(@registered_build_dependencies, @side_effects)
       @user_deps = {}
       # Hash of builder name (String) => builder class (Class).
       @builders = {}
@@ -260,16 +260,16 @@ module Rscons
       end
       failure = nil
       begin
-        while @job_set.size > 0 or @threaded_commands.size > 0
+        while @builder_set.size > 0 or @threaded_commands.size > 0
 
           if failure
-            @job_set.clear!
+            @builder_set.clear
             builder = nil
           else
             targets_still_building = @threaded_commands.map do |tc|
               tc.builder.target
             end
-            builder = @job_set.get_next_job_to_run(targets_still_building)
+            builder = @builder_set.get_next_builder_to_run(targets_still_building)
           end
 
           # TODO: have Cache determine when checksums may be invalid based on
@@ -328,7 +328,7 @@ module Rscons
     #
     # @return [void]
     def clear_targets
-      @job_set.clear!
+      @builder_set.clear
     end
 
     # Define a build target.
@@ -356,7 +356,7 @@ module Rscons
           cache: Cache.instance,
           env: self,
           vars: vars)
-        @job_set.add_job(builder)
+        @builder_set << builder
         builder
       else
         super
diff --git a/lib/rscons/job_set.rb b/lib/rscons/job_set.rb
deleted file mode 100644
index 6b0254b..0000000
--- a/lib/rscons/job_set.rb
+++ /dev/null
@@ -1,87 +0,0 @@
-module Rscons
-  # Class to keep track of a set of jobs that need to be performed.
-  class JobSet
-
-    # Create a JobSet
-    #
-    # @param build_dependencies [Hash]
-    #   Hash mapping targets to a set of build dependencies. A job will not be
-    #   returned as ready to run if any of its dependencies are still building.
-    # @param side_effects [Hash]
-    #   Hash mapping targets to a set of side-effect files. A job will not be
-    #   returned as ready to run if any of its dependencies is a side-effect
-    #   of another target that has not yet been built.
-    def initialize(build_dependencies, side_effects)
-      @jobs = {}
-      @build_dependencies = build_dependencies
-      @side_effects = side_effects
-    end
-
-    # Add a job to the JobSet.
-    #
-    # @param builder [Builder]
-    #   The {Builder} that will produce the target.
-    def add_job(builder)
-      # We allow multiple jobs to be registered per target for cases like:
-      #   env.Directory("dest")
-      #   env.Install("dest", "bin")
-      #   env.Install("dest", "share")
-      @jobs[builder.target] ||= []
-      @jobs[builder.target] << builder
-    end
-
-    # Get the next job that is ready to run from the JobSet.
-    #
-    # This method will remove the job from the JobSet.
-    #
-    # @param targets_still_building [Array<String>]
-    #   Targets that are not finished building. This is used to avoid returning
-    #   a job as available to run if it depends on one of the targets that are
-    #   still building as a source.
-    #
-    # @return [nil, Builder]
-    #   The next job to run.
-    def get_next_job_to_run(targets_still_building)
-      not_built_yet = targets_still_building + @jobs.keys
-      not_built_yet += not_built_yet.reduce([]) do |result, target|
-        result + (@side_effects[target] || [])
-      end
-
-      target_to_build = @jobs.keys.find do |target|
-        deps = @jobs[target][0].sources + (@build_dependencies[target] || []).to_a
-        !deps.find {|dep| not_built_yet.include?(dep)}
-      end
-
-      if target_to_build
-        builder = @jobs[target_to_build][0]
-        if @jobs[target_to_build].size > 1
-          @jobs[target_to_build].slice!(0)
-        else
-          @jobs.delete(target_to_build)
-        end
-        return builder
-      end
-
-      # If there is a job to run, and nothing is still building, but we did
-      # not find a job to run above, then there might be a circular dependency
-      # introduced by the user.
-      if (@jobs.size > 0) and targets_still_building.empty?
-        raise "Could not find a runnable job. Possible circular dependency for #{@jobs.keys.first}"
-      end
-    end
-
-    # Remove all jobs from the JobSet.
-    def clear!
-      @jobs.clear
-    end
-
-    # Get the JobSet size.
-    #
-    # @return [Integer]
-    #   JobSet size.
-    def size
-      @jobs.size
-    end
-
-  end
-end