diff --git a/shared/macros/10-bash.jinja b/shared/macros/10-bash.jinja
index 82ac231dfac..17ed7a13c7a 100644
--- a/shared/macros/10-bash.jinja
+++ b/shared/macros/10-bash.jinja
@@ -1937,7 +1937,7 @@ Part of the grub2_bootloader_argument template.
 {{%- macro update_etc_default_grub_manually_absent(arg_name) -%}}
 # Correct the form of default kernel command line in GRUB
 if grep -q '^GRUB_CMDLINE_LINUX=.*{{{ arg_name }}}=.*"'  '/etc/default/grub' ; then
-       sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\){{{ arg_name }}}=?[^[:space:]]*\(.*"\)/\1 \2/' '/etc/default/grub'
+       sed -i 's/\(^GRUB_CMDLINE_LINUX=".*\){{{ arg_name }}}=\?[^[:space:]]*\(.*"\)/\1 \2/' '/etc/default/grub'
 fi
 {{%- endmacro %}}