diff --git a/lib/jekyll/site.rb b/lib/jekyll/site.rb
index 5797df77..87ea719b 100644
--- a/lib/jekyll/site.rb
+++ b/lib/jekyll/site.rb
@@ -435,7 +435,7 @@ module Jekyll
     private
     def configure_include_paths
       @includes_load_paths = Array(in_source_dir(config["includes_dir"].to_s))
-      @includes_load_paths << theme.includes_path if self.theme
+      @includes_load_paths << theme.includes_path if theme && theme.includes_path
     end
 
     private
diff --git a/test/helper.rb b/test/helper.rb
index bb9e5a29..ca60f79f 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -74,6 +74,10 @@ module DirectoryHelpers
     test_dir("source", *subdirs)
   end
 
+  def theme_dir(*subdirs)
+    test_dir("fixtures", "test-theme", *subdirs)
+  end
+
   def test_dir(*subdirs)
     root_dir("test", *subdirs)
   end
diff --git a/test/test_site.rb b/test/test_site.rb
index bbf42d25..65032ebd 100644
--- a/test/test_site.rb
+++ b/test/test_site.rb
@@ -49,6 +49,18 @@ class TestSite < JekyllUnitTest
       site = Site.new(site_configuration({ "baseurl" => "/blog" }))
       assert_equal "/blog", site.baseurl
     end
+
+    should "only include theme includes_path if the path exists" do
+      site = fixture_site({ "theme" => "test-theme" })
+      assert_equal [source_dir("_includes"), theme_dir("_includes")],
+        site.includes_load_paths
+
+      allow(File).to receive(:directory?).with(theme_dir("_sass")).and_return(true)
+      allow(File).to receive(:directory?).with(theme_dir("_layouts")).and_return(true)
+      allow(File).to receive(:directory?).with(theme_dir("_includes")).and_return(false)
+      site = fixture_site({ "theme" => "test-theme" })
+      assert_equal [source_dir("_includes")], site.includes_load_paths
+    end
   end
   context "creating sites" do
     setup do
diff --git a/test/test_theme.rb b/test/test_theme.rb
index ab1eff43..3d557dc8 100644
--- a/test/test_theme.rb
+++ b/test/test_theme.rb
@@ -3,7 +3,6 @@ require "helper"
 class TestTheme < JekyllUnitTest
   def setup
     @theme = Theme.new("test-theme")
-    @expected_root = File.expand_path "./fixtures/test-theme", File.dirname(__FILE__)
   end
 
   context "initializing" do
@@ -13,7 +12,7 @@ class TestTheme < JekyllUnitTest
     end
 
     should "know the theme root" do
-      assert_equal @expected_root, @theme.root
+      assert_equal theme_dir, @theme.root
     end
 
     should "know the theme version" do
@@ -36,13 +35,13 @@ class TestTheme < JekyllUnitTest
   context "path generation" do
     [:assets, :_layouts, :_includes, :_sass].each do |folder|
       should "know the #{folder} path" do
-        expected = File.expand_path(folder.to_s, @expected_root)
+        expected = theme_dir(folder.to_s)
         assert_equal expected, @theme.public_send("#{folder.to_s.tr("_", "")}_path")
       end
     end
 
     should "generate folder paths" do
-      expected = File.expand_path("./_sass", @expected_root)
+      expected = theme_dir("_sass")
       assert_equal expected, @theme.send(:path_for, :_sass)
     end
 
@@ -58,7 +57,7 @@ class TestTheme < JekyllUnitTest
       # no support for symlinks on Windows
       skip_if_windows "Jekyll does not currently support symlinks on Windows."
 
-      expected = File.expand_path("./_layouts", @expected_root)
+      expected = theme_dir("_layouts")
       assert_equal expected, @theme.send(:path_for, :_symlink)
     end
   end