diff --git a/.gitea/workflows/gitea-main-ci.yaml b/.gitea/workflows/gitea-main-ci.yaml
index 76d2a62..21fc77d 100644
--- a/.gitea/workflows/gitea-main-ci.yaml
+++ b/.gitea/workflows/gitea-main-ci.yaml
@@ -135,6 +135,14 @@ jobs:
             [ -n "$safe_branch" ] || safe_branch="branch"
             version="${safe_branch}-${short_sha}"
           fi
+          # Lowercase the whole thing. image_version is BOTH the OCI tag AND the
+          # in-artifact UKI filename (fleet-<version>.efi) + verity.json + subnqn.
+          # A registry may lowercase the pushed TAG while the artifact keeps the
+          # original case, so a mixed-case branch (e.g. SPDK-permanence) yields a
+          # capital fleet-SPDK-…​.efi the lowercase boot URL can't fetch (iPXE
+          # "no such file"). Forcing lowercase keeps tag, filename, verity.json,
+          # and the dnsmasq boot URL all in agreement.
+          version="$(printf '%s' "$version" | tr '[:upper:]' '[:lower:]')"
           echo "image_version=${version}" >> "$GITHUB_OUTPUT"
           echo "Building image_version=${version}"