diff --git a/lib/linguist/diff.rb b/lib/linguist/diff.rb
deleted file mode 100644
index 759fc7e7..00000000
--- a/lib/linguist/diff.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-module HashDiff
-  def deep_diff(b)
-    a = self
-    (a.keys | b.keys).inject({}) do |diff, k|
-      if a[k] != b[k]
-        if a[k].respond_to?(:deep_diff) && b[k].respond_to?(:deep_diff)
-          diff[k] = a[k].deep_diff(b[k])
-        else
-          diff[k] = [a[k], b[k]]
-        end
-      end
-      diff
-    end
-  end
-end
-
-class Hash
-  include HashDiff
-end