diff --git a/docker/Dockerfile b/docker/Dockerfile
index 3b37eeb..5860eaf 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,9 +1,9 @@
 FROM debian:bookworm-slim AS build
 
-# Pin Hugo (extended). apk's `hugo` floats: it reached 0.160, which removed the
-# .Site.Author field still referenced by the hextra theme's RSS template, breaking
-# every build. Pin to a known-good version until the theme is bumped.
-ARG HUGO_VERSION=0.155.0
+# Pin Hugo (extended) for reproducible builds — apk's `hugo` floats and previously
+# broke the site when it bumped past a theme-incompatible release. Keep this at/above
+# the hextra theme's min_version (see themes/hextra/theme.toml).
+ARG HUGO_VERSION=0.163.2
 ARG TARGETARCH
 RUN apt-get update \
     && apt-get install -y --no-install-recommends curl ca-certificates \
diff --git a/themes/hextra b/themes/hextra
index 46290e1..8e53e7a 160000
--- a/themes/hextra
+++ b/themes/hextra
@@ -1 +1 @@
-Subproject commit 46290e10e71d23c0ac4cfd280986dd8ebcfce00f
+Subproject commit 8e53e7a7ef3e24348edbac276e03cb9fecf66d0c