diff --git a/lib/hyperclient/link.rb b/lib/hyperclient/link.rb
index c660ed5..fa98cf8 100644
--- a/lib/hyperclient/link.rb
+++ b/lib/hyperclient/link.rb
@@ -1,6 +1,7 @@
 require 'hyperclient/resource'
 require 'uri_template'
 require 'futuroscope'
+require_relative '../uri_template/rfc6570/expression'
 
 module Hyperclient
   # Internal: The Link is used to let a Resource interact with the API.
diff --git a/lib/uri_template/rfc6570/expression.rb b/lib/uri_template/rfc6570/expression.rb
new file mode 100644
index 0000000..1e20351
--- /dev/null
+++ b/lib/uri_template/rfc6570/expression.rb
@@ -0,0 +1,24 @@
+require 'uri_template/rfc6570/expression'
+
+class URITemplate::RFC6570
+  class Expression < Token
+    def expand(vars)
+      unused_vars = vars.keys.dup
+      result = []
+      @variable_specs.each do |var, expand, max_length|
+        if Utils.def?(vars[var])
+          result.push(*expand_one(var, vars[var], expand, max_length))
+        end
+        unused_vars.delete(var)
+      end
+      unused_vars.each do |k|
+        result.push(*expand_one(k, vars[k], false, 0))
+      end
+      if result.any?
+        return (self.class::PREFIX + result.join(self.class::SEPARATOR))
+      else
+        return ''
+      end
+    end
+  end
+end