Use nullptr instead of NULL
diff --git a/src/test-size-params.cc b/src/test-size-params.cc
index 35d9e3c..faa8280 100644
--- a/src/test-size-params.cc
+++ b/src/test-size-params.cc
@@ -43,7 +43,7 @@
 int
 main (int argc, char **argv)
 {
-  hb_blob_t *blob = NULL;
+  hb_blob_t *blob = nullptr;
 
   if (argc != 2) {
     fprintf (stderr, "usage: %s font-file\n", argv[0]);
@@ -59,7 +59,7 @@
     hb_memory_mode_t mm;
 
 #ifdef HAVE_GLIB
-    GMappedFile *mf = g_mapped_file_new (argv[1], false, NULL);
+    GMappedFile *mf = g_mapped_file_new (argv[1], false, nullptr);
     font_data = g_mapped_file_get_contents (mf);
     len = g_mapped_file_get_length (mf);
     destroy = (hb_destroy_func_t) g_mapped_file_unref;
@@ -85,7 +85,7 @@
   /* Create the face */
   hb_face_t *face = hb_face_create (blob, 0 /* first face */);
   hb_blob_destroy (blob);
-  blob = NULL;
+  blob = nullptr;
 
   unsigned int p[5];
   bool ret = hb_ot_layout_get_size_params (face, p, p+1, p+2, p+3, p+4);