diff --git a/.travis.yml b/.travis.yml
index 2e65057..2bf1488 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,6 +4,7 @@ rvm:
   - 1.9.3
   - 2.0.0
   - 2.1.0
+  - 2.7.1
   - jruby-19mode
   - rbx-19mode
   - ruby-head
diff --git a/Gemfile.lock b/Gemfile.lock
index 98a84bc..c3641db 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -101,7 +101,7 @@ GEM
       equalizer (~> 0.0.7)
       parser (~> 2.1.0)
       procto (~> 0.0.2)
-    yard (0.8.7.3)
+    yard (0.9.25)
 
 PLATFORMS
   java
@@ -120,3 +120,6 @@ DEPENDENCIES
   simplecov-console
   uri_template!
   yard
+
+BUNDLED WITH
+   2.1.4
diff --git a/lib/uri_template/rfc6570/expression.rb b/lib/uri_template/rfc6570/expression.rb
index e8125ff..b81345b 100644
--- a/lib/uri_template/rfc6570/expression.rb
+++ b/lib/uri_template/rfc6570/expression.rb
@@ -20,7 +20,8 @@
 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
-require 'uri_template/rfc6570'
+
+require 'uri_template/rfc6570' unless defined? URITemplate::RFC6570
 
 class URITemplate::RFC6570
 
diff --git a/lib/uri_template/rfc6570/expression/named.rb b/lib/uri_template/rfc6570/expression/named.rb
index 22c2d1f..1ca9440 100644
--- a/lib/uri_template/rfc6570/expression/named.rb
+++ b/lib/uri_template/rfc6570/expression/named.rb
@@ -21,7 +21,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-require 'uri_template/rfc6570'
+require 'uri_template/rfc6570' unless defined? URITemplate::RFC6570
 
 class URITemplate::RFC6570
 
@@ -65,7 +65,6 @@ def to_r_source
   def expand_partial( vars )
     result = []
     rest   = []
-    defined = false
     @variable_specs.each do | var, expand , max_length |
       if vars.key? var
         if Utils.def? vars[var]
diff --git a/lib/uri_template/rfc6570/expression/unnamed.rb b/lib/uri_template/rfc6570/expression/unnamed.rb
index c20ab59..16d8c8a 100644
--- a/lib/uri_template/rfc6570/expression/unnamed.rb
+++ b/lib/uri_template/rfc6570/expression/unnamed.rb
@@ -21,7 +21,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-require 'uri_template/rfc6570'
+require 'uri_template/rfc6570' unless defined? URITemplate::RFC6570
 
 class URITemplate::RFC6570::Expression::Unnamed < URITemplate::RFC6570::Expression
 
diff --git a/lib/uri_template/rfc6570/regex_builder.rb b/lib/uri_template/rfc6570/regex_builder.rb
index a9751c2..cf4fd75 100644
--- a/lib/uri_template/rfc6570/regex_builder.rb
+++ b/lib/uri_template/rfc6570/regex_builder.rb
@@ -21,7 +21,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-require 'uri_template/rfc6570'
+require 'uri_template/rfc6570' unless defined? URITemplate::RFC6570
 
 class URITemplate::RFC6570