diff --git a/example/jsonptr/jsonptr.cc b/example/jsonptr/jsonptr.cc
index 7641b05..c3d842c 100644
--- a/example/jsonptr/jsonptr.cc
+++ b/example/jsonptr/jsonptr.cc
@@ -1122,7 +1122,7 @@
   }
 
   if (!g_flags.output_cbor_metadata_as_json_comments) {
-    return nullptr;
+    return write_dst("null", 4);
   }
   uint8_t buf[WUFFS_BASE__U64__BYTE_LENGTH__MAX_INCL];
   size_t n = wuffs_base__render_number_u64(