diff --git a/tools/boot/bookworm/common.sh b/tools/boot/bookworm/common.sh
index 0499b45d..657415a9 100644
--- a/tools/boot/bookworm/common.sh
+++ b/tools/boot/bookworm/common.sh
@@ -257,8 +257,10 @@ change_grub_cfg_uuid () {
     # reliable - see #1024346 and #1024720 for examples where this
     # fails. Instead, let's generate a UUID here and use that as a
     # flag file.
-    UUID=$(uuidgen)
-    mkdir -p $CDDIR/.disk/id
-    touch $CDDIR/.disk/id/$UUID
-    sed -i "/search --file --set=root/s,.disk/info,.disk/id/$UUID," $CDDIR/EFI/debian/grub.cfg
+    if [ -f $CDDIR/EFI/debian/grub.cfg ]; then
+	UUID=$(uuidgen)
+	mkdir -p $CDDIR/.disk/id
+	touch $CDDIR/.disk/id/$UUID
+	sed -i "/search --file --set=root/s,.disk/info,.disk/id/$UUID," $CDDIR/EFI/debian/grub.cfg
+    fi
 }
diff --git a/tools/boot/bullseye/common.sh b/tools/boot/bullseye/common.sh
index 33556b89..f3310d28 100644
--- a/tools/boot/bullseye/common.sh
+++ b/tools/boot/bullseye/common.sh
@@ -231,8 +231,10 @@ change_grub_cfg_uuid () {
     # reliable - see #1024346 and #1024720 for examples where this
     # fails. Instead, let's generate a UUID here and use that as a
     # flag file.
-    UUID=$(uuidgen)
-    mkdir -p $CDDIR/.disk/id
-    touch $CDDIR/.disk/id/$UUID
-    sed -i "/search --file --set=root/s,.disk/info,.disk/id/$UUID," $CDDIR/EFI/debian/grub.cfg
+    if [ -f $CDDIR/EFI/debian/grub.cfg ]; then
+	UUID=$(uuidgen)
+	mkdir -p $CDDIR/.disk/id
+	touch $CDDIR/.disk/id/$UUID
+	sed -i "/search --file --set=root/s,.disk/info,.disk/id/$UUID," $CDDIR/EFI/debian/grub.cfg
+    fi
 }