diff --git a/lib/puppet/file_collection.rb b/lib/puppet/file_collection.rb
index 69f59ffdf..7db2600c0 100644
--- a/lib/puppet/file_collection.rb
+++ b/lib/puppet/file_collection.rb
@@ -1,28 +1,30 @@
 # A simple way to turn file names into singletons,
 # so we don't have tons of copies of each file path around.
 class Puppet::FileCollection
     require 'puppet/file_collection/lookup'
 
     def self.collection
         @collection
     end
 
     def initialize
         @paths = []
+        @inverse = {}
     end
 
     def index(path)
-        if @paths.include?(path)
-            return @paths.index(path)
+        if i = @inverse[path]
+            return i
         else
             @paths << path
-            return @paths.length - 1
+            i = @inverse[path] = @paths.length - 1
+            return i
         end
     end
 
     def path(index)
         @paths[index]
     end
 
     @collection = self.new
 end