diff --git a/.gitignore b/.gitignore
index c3c96b6..3604ac0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@ pkg
 doc
 .yardoc
 coverage
+vendor
\ No newline at end of file
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index edbc913..8aa74b5 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -8,7 +8,8 @@ if !RUBY_VERSION.start_with? '1.8'
     Coveralls::SimpleCov::Formatter
   ]
   SimpleCov.start do
-    add_filter "/spec/"
+    add_filter '/spec/'    # exclude test code
+    add_filter '/vendor/'  # exclude gems which are vendored on Travis CI
   end
 
   # Remove Docile, which was required by SimpleCov, to require again later