diff --git a/.gitignore b/.gitignore
index 34ac308..3877c6b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@
 /build/
 /tests/t???
 /tests/t???.c
+/tests/.bundle/
diff --git a/tests/Gemfile b/tests/Gemfile
index 6b7f7ca..4a05f85 100644
--- a/tests/Gemfile
+++ b/tests/Gemfile
@@ -1 +1,3 @@
+source "https://rubygems.org"
+
 gem "rspec"
diff --git a/tests/Gemfile.lock b/tests/Gemfile.lock
index b5023a7..0b820d8 100644
--- a/tests/Gemfile.lock
+++ b/tests/Gemfile.lock
@@ -1,4 +1,5 @@
 GEM
+  remote: https://rubygems.org/
   specs:
     diff-lcs (1.3)
     rspec (3.6.0)