diff --git a/qemu-nbd.c b/qemu-nbd.c
index fe6053ca56..136e8c9c05 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -79,6 +79,7 @@ static void usage(const char *name)
 #endif
 "\n"
 "Block device options:\n"
+"  -f, --format=FORMAT  set image format (raw, qcow2, ...)\n"
 "  -r, --read-only      export read-only\n"
 "  -s, --snapshot       use FILE as an external snapshot, create a temporary\n"
 "                       file with backing_file=FILE, redirect the write to\n"
diff --git a/qemu-nbd.texi b/qemu-nbd.texi
index 5b55f769ac..0a7e01385c 100644
--- a/qemu-nbd.texi
+++ b/qemu-nbd.texi
@@ -22,6 +22,8 @@ Export QEMU disk image using NBD protocol.
   interface to bind to (default @samp{0.0.0.0})
 @item -k, --socket=@var{path}
   Use a unix socket with path @var{path}
+@item -f, --format=@var{format}
+  Set image format as @var{format}
 @item -r, --read-only
   export read-only
 @item -P, --partition=@var{num}