diff --git a/lib/cpp/test/OpenSSLManualInitTest.cpp b/lib/cpp/test/OpenSSLManualInitTest.cpp
index a30b303..a751806 100644
--- a/lib/cpp/test/OpenSSLManualInitTest.cpp
+++ b/lib/cpp/test/OpenSSLManualInitTest.cpp
@@ -62,7 +62,7 @@
   // uninitialized.  It might also fail on very old versions of
   // OpenSSL...
   const EVP_MD* md = EVP_get_digestbyname("SHA256");
-  BOOST_CHECK(md != NULL);
+  BOOST_CHECK(md != nullptr);
   openssl_cleanup();
 }