diff --git a/Dockerfile b/Dockerfile
index ba7687e..f59be33 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -15,7 +15,7 @@ ARG PYTHON_VERSION=3.14.5
 # renovate: datasource=github-releases depName=upx/upx versioning=loose
 ARG UPX_VERSION=5.1.1
 
-RUN --mount=from=ghcr.io/sigstore/cosign/cosign:v3.0.6@sha256:de9c65609e6bde17e6b48de485ee788407c9502fa08b8f4459f595b21f56cd00,source=/ko-app/cosign,target=/usr/bin/cosign \
+RUN --mount=from=ghcr.io/sigstore/cosign/cosign:v3.1.1@sha256:6bbe0d281d955c79f85b325f0f7e651c1bcab5a4fa4ad4903d74955178a3b2eb,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}" \