diff --git a/test/test_document.rb b/test/test_document.rb
index 108f55cc..e980b1f5 100644
--- a/test/test_document.rb
+++ b/test/test_document.rb
@@ -39,7 +39,7 @@ class TestDocument < JekyllUnitTest
     end
 
     should "exist" do
-      refute @document.nil?
+      refute_nil @document
     end
 
     should "know its relative path" do
diff --git a/test/test_utils.rb b/test/test_utils.rb
index 40549aa8..969ffaa1 100644
--- a/test/test_utils.rb
+++ b/test/test_utils.rb
@@ -130,7 +130,7 @@ class TestUtils < JekyllUnitTest
 
   context "The \`Utils.slugify\` method" do
     should "return nil if passed nil" do
-      assert Utils.slugify(nil).nil?
+      assert_nil Utils.slugify(nil)
     rescue NoMethodError
       assert false, "Threw NoMethodError"
     end