diff --git a/doc/README.gpt b/doc/README.gpt
index 0a3286f..543bf87 100644
--- a/doc/README.gpt
+++ b/doc/README.gpt
@@ -220,6 +220,16 @@ board/sandbox/README.sandbox:
 => gpt flip host 0
 [ . . . ]
 
+The GPT functionality may be tested with the 'sandbox' board by
+creating a disk image as described under 'Block Device Emulation' in
+board/sandbox/README.sandbox:
+
+=>host bind 0 ./disk.raw
+=> gpt read host 0
+[ . . . ]
+=> gpt flip host 0
+[ . . . ]
+
 Partition type GUID:
 ====================