diff --git a/package/linux/amd64/Dockerfile b/package/linux/amd64/Dockerfile
index 37af11b..e0f410b 100644
--- a/package/linux/amd64/Dockerfile
+++ b/package/linux/amd64/Dockerfile
@@ -1,6 +1,11 @@
-FROM ubuntu:26.04
+# syntax=docker/dockerfile:1.7
+FROM ubuntu:26.04@sha256:2260313b31c8c011cd2eebe728008efac1b3982be73eb71348ea2648d2c0e09b
 
-ARG UBUNTU_MIRROR=http://archive.ubuntu.com/ubuntu
+ARG UBUNTU_SNAPSHOT=20260825T000000Z
+
+ADD --checksum=sha256:6077d27c6b6f8b23590cb01ff877ed8c804a67a5442cc32b5a33da10d2bd0e90 \
+    https://snapshot.ubuntu.com/ubuntu/20260825T000000Z/pool/main/c/ca-certificates/ca-certificates_20260601~26.04.1_all.deb \
+    /tmp/ca-certificates.deb
 ARG IMAGE_VERSION=dev
 
 LABEL org.opencontainers.image.source="https://github.com/PastureStack/internal-dns" \
@@ -9,11 +14,14 @@ LABEL org.opencontainers.image.source="https://github.com/PastureStack/internal-
       org.opencontainers.image.version="${IMAGE_VERSION}"
 
 RUN set -eux; \
+    mkdir -p /tmp/ca-bootstrap /etc/ssl/certs; \
+    dpkg-deb --extract /tmp/ca-certificates.deb /tmp/ca-bootstrap; \
+    find /tmp/ca-bootstrap/usr/share/ca-certificates -type f -name '*.crt' | LC_ALL=C sort | while IFS= read -r certificate; do sed -e '$a\' "${certificate}"; done > /etc/ssl/certs/ca-certificates.crt; \
+    rm -rf /tmp/ca-bootstrap /tmp/ca-certificates.deb; \
     rm -f /usr/bin/pebble; \
-    find /etc/apt -type f \( -name '*.list' -o -name '*.sources' \) -exec sed -i \
-        -e "s|http://security.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" \
-        -e "s|http://archive.ubuntu.com/ubuntu|${UBUNTU_MIRROR}|g" {} +; \
-    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\n' > /etc/apt/apt.conf.d/80pasturestack-retries; \
+    rm -f /etc/apt/sources.list /etc/apt/sources.list.d/*.list /etc/apt/sources.list.d/*.sources; \
+    printf 'Types: deb\nURIs: https://snapshot.ubuntu.com/ubuntu/%s\nSuites: resolute resolute-updates resolute-backports resolute-security\nComponents: main universe restricted multiverse\nSigned-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg\nSnapshot: no\n' "${UBUNTU_SNAPSHOT}" > /etc/apt/sources.list.d/pasturestack-snapshot.sources; \
+    printf 'Acquire::Retries "5";\nAcquire::http::Timeout "30";\nAcquire::https::Timeout "30";\nAcquire::http::Pipeline-Depth "0";\nAcquire::https::CaInfo "/etc/ssl/certs/ca-certificates.crt";\nAcquire::https::Verify-Peer "true";\nAcquire::https::Verify-Host "true";\nAcquire::AllowInsecureRepositories "false";\nAPT::Get::AllowUnauthenticated "false";\n' > /etc/apt/apt.conf.d/80pasturestack-snapshot; \
     apt-get update; \
     apt-get install -y --no-install-recommends ca-certificates curl openssl tini; \
     rm -rf /var/lib/apt/lists/*; \
diff --git a/package/windows/amd64/Dockerfile b/package/windows/amd64/Dockerfile
index dee4eed..6cf86e0 100644
--- a/package/windows/amd64/Dockerfile
+++ b/package/windows/amd64/Dockerfile
@@ -1,5 +1,5 @@
 # escape=`
-FROM mcr.microsoft.com/windows/nanoserver:ltsc2022
+FROM mcr.microsoft.com/windows/nanoserver:ltsc2022@sha256:e4ce8c20390c3785c3cbeef15c579d186b3599d37525c596590cf4508e38d3ff
 
 WORKDIR C:\pasturestack
 COPY internal-dns.exe C:\pasturestack\internal-dns.exe