diff --git a/TODO b/TODO
index 8e3a184a5..3938a98fc 100644
--- a/TODO
+++ b/TODO
@@ -161,6 +161,7 @@ Allow swap space from the guest to be used.  Is it a good idea?
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 Allow memsize to be configured (ie. guestfs_set_memsize etc)
+Also have an environment variable (LIBGUESTFS_MEMSIZE).
 
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