diff --git a/utils_unittest.cc b/utils_unittest.cc
index 77a7d9b..3103349 100644
--- a/utils_unittest.cc
+++ b/utils_unittest.cc
@@ -198,6 +198,20 @@
   EXPECT_TRUE(utils::RecursiveUnlinkDir(temp_dir));
 }
 
+TEST(UtilsTest, IsDirTest) {
+  string temp_dir;
+  EXPECT_TRUE(utils::MakeTempDirectory("isdir-test.XXXXXX", &temp_dir));
+  string temp_file = temp_dir + "temp-file";
+  EXPECT_TRUE(utils::WriteFile(temp_file.c_str(), "", 0));
+  string temp_symlink = temp_dir + "temp-symlink";
+  EXPECT_EQ(0, symlink(temp_dir.c_str(), temp_symlink.c_str()));
+  EXPECT_TRUE(utils::IsDir(temp_dir.c_str()));
+  EXPECT_FALSE(utils::IsDir(temp_file.c_str()));
+  EXPECT_FALSE(utils::IsDir(temp_symlink.c_str()));
+  EXPECT_FALSE(utils::IsDir("/non/existent/path"));
+  ASSERT_TRUE(utils::RecursiveUnlinkDir(temp_dir));
+}
+
 TEST(UtilsTest, TempFilenameTest) {
   const string original = "/foo.XXXXXX";
   const string result = utils::TempFilename(original);