diff --git a/Dockerfile b/Dockerfile
index 1aba6d4..58a9024 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -15,7 +15,7 @@ ARG PYTHON_VERSION=3.14.2
 # renovate: datasource=github-releases depName=upx/upx versioning=loose
 ARG UPX_VERSION=5.0.2
 
-RUN --mount=from=ghcr.io/sigstore/cosign/cosign:v3.0.3@sha256:774391ac9f0c137ee419ce56522df5fd3b1f52be90c5b77e97f7c053bdd67a67,source=/ko-app/cosign,target=/usr/bin/cosign \
+RUN --mount=from=ghcr.io/sigstore/cosign/cosign:v3.0.4@sha256:0b015a3557a64a751712da8a6395534160018eaaa2d969882a85a336de9adb70,source=/ko-app/cosign,target=/usr/bin/cosign \
   umask 0 && cd /tmp/helper && \
   curl --fail-with-body -LOO \
     "https://www.python.org/ftp/python/${PYTHON_VERSION}/python-${PYTHON_VERSION}-amd64.exe{,.sigstore}" \