diff --git a/build_library/grub.cfg b/build_library/grub.cfg
index 90c7675cb4..a016875262 100644
--- a/build_library/grub.cfg
+++ b/build_library/grub.cfg
@@ -69,6 +69,9 @@ fi
 if [ -f "($root)/flatcar/first_boot" ]; then
     set first_boot="flatcar.first_boot=detected"
 fi
+if [ -f "($root)/coreos/first_boot" ]; then
+    set first_boot="flatcar.first_boot=detected"
+fi
 
 # Determine if the disk GUID needs to be randomized.
 search --no-floppy --set randomize_disk_guid \