diff --git a/lib/qemu.c b/lib/qemu.c
index 15e729839..b8cc9c5a1 100644
--- a/lib/qemu.c
+++ b/lib/qemu.c
@@ -80,6 +80,7 @@ generic_qmp_test (guestfs_h *g, const char *qmp_command, char **outp)
   guestfs_int_cmd_add_string_unquoted (cmd, "QEMU_AUDIO_DRV=none ");
   guestfs_int_cmd_add_string_quoted (cmd, g->hv);
   guestfs_int_cmd_add_string_unquoted (cmd, " -display none");
+  guestfs_int_cmd_add_string_unquoted (cmd, " -cpu max");
   guestfs_int_cmd_add_string_unquoted (cmd, " -machine ");
   guestfs_int_cmd_add_string_quoted (cmd,
 #ifdef MACHINE_TYPE
diff --git a/tests/disks/debug-qemu.sh b/tests/disks/debug-qemu.sh
index e6e80abe3..96c90553b 100755
--- a/tests/disks/debug-qemu.sh
+++ b/tests/disks/debug-qemu.sh
@@ -25,7 +25,7 @@ fi
 
 # The direct backend runs qemu ... -qmp stdio to query for KVM.  For
 # the test to pass we have to provide an answer here.
-if [ "x$5" = "x-qmp" ]; then
+if [ "x$7" = "x-qmp" ]; then
     # Consume stdin first.
     cat >/dev/null
     # Write some fake output.