diff --git a/features/_usi/initrd.include/usr/bin/persist b/features/_usi/initrd.include/usr/bin/persist
index ed792e09..34589c3b 100755
--- a/features/_usi/initrd.include/usr/bin/persist
+++ b/features/_usi/initrd.include/usr/bin/persist
@@ -76,6 +76,7 @@ export HOME=/root
 
 # setup OCI_TAG, UKI_SHA and fetch UKI
 OCI_TAG="$GARDENLINUX_VERSION-$GARDENLINUX_CNAME-$GARDENLINUX_COMMIT_ID-$OCI_ARCH"
+OCI_TAG=${OCI_TAG//_/-} # replace underscores with dashes
 UKI_SHA=$(oras manifest fetch "$OCI_REPO:${OCI_TAG}" | jq -r '.layers[] | select(.mediaType=="application/io.gardenlinux.uki") | .digest')
 oras blob fetch "$OCI_REPO@$UKI_SHA" -o "$esp_dir/EFI/Linux/uki.efi"