diff --git a/tests/sys_xattr_test.cpp b/tests/sys_xattr_test.cpp
index 113ec26..006e840 100644
--- a/tests/sys_xattr_test.cpp
+++ b/tests/sys_xattr_test.cpp
@@ -107,7 +107,7 @@
   ASSERT_EQ(0, fsetxattr(tf.fd, "user.foo", "bar", 4, 0));
   ssize_t result = flistxattr(tf.fd, buf, sizeof(buf));
   ASSERT_TRUE(result >= 9);
-  ASSERT_TRUE(memmem(buf, sizeof(buf), "user.foo", 9) != NULL);
+  ASSERT_TRUE(memmem(buf, sizeof(buf), "user.foo", 9) != nullptr);
 }
 
 TEST(sys_xattr, flistattr_opath) {
@@ -120,7 +120,7 @@
 #if defined(__BIONIC__)
   ASSERT_TRUE(res >= 9);
   ASSERT_TRUE(static_cast<size_t>(res) <= sizeof(buf));
-  ASSERT_TRUE(memmem(buf, res, "user.foo", 9) != NULL);
+  ASSERT_TRUE(memmem(buf, res, "user.foo", 9) != nullptr);
 #else
   ASSERT_EQ(-1, res);
   ASSERT_EQ(EBADF, errno);