diff --git a/lib/railsless_rake_task_runner.rb b/lib/railsless_rake_task_runner.rb
index a1f17a7..94aae13 100644
--- a/lib/railsless_rake_task_runner.rb
+++ b/lib/railsless_rake_task_runner.rb
@@ -10,35 +10,37 @@ def self.load_rails
   end
 end
 
-# Try to run no-rails tasks first. Fallback to rails if none is found.
-Rake.application.instance_eval do
-  module Rake
-    class Task
-      alias :old_lookup_prerequisite :lookup_prerequisite
+if defined?(Rake)
+  # Try to run no-rails tasks first. Fallback to rails if none is found.
+  Rake.application.instance_eval do
+    module Rake
+      class Task
+        alias :old_lookup_prerequisite :lookup_prerequisite
 
-      def lookup_prerequisite(prerequisite_name)
-        if prerequisite_name == "environment" && !Rake.application.lookup(prerequisite_name)
-          RailslessRakeTaskRunner.load_rails
+        def lookup_prerequisite(prerequisite_name)
+          if prerequisite_name == "environment" && !Rake.application.lookup(prerequisite_name)
+            RailslessRakeTaskRunner.load_rails
+          end
+          old_lookup_prerequisite(prerequisite_name)
         end
-        old_lookup_prerequisite(prerequisite_name)
       end
     end
-  end
 
-  def top_level
-    if running_a_task? && requested_tasks_exist?
-      super
-    else
-      RailslessRakeTaskRunner.load_rails
-      super
+    def top_level
+      if running_a_task? && requested_tasks_exist?
+        super
+      else
+        RailslessRakeTaskRunner.load_rails
+        super
+      end
     end
-  end
 
-  def running_a_task?
-    !(options.show_tasks || options.show_prereqs)
-  end
+    def running_a_task?
+      !(options.show_tasks || options.show_prereqs)
+    end
 
-  def requested_tasks_exist?
-    top_level_tasks.any? { |task| lookup(task) }
+    def requested_tasks_exist?
+      top_level_tasks.any? { |task| lookup(task) }
+    end
   end
 end