diff --git a/docker-build-runner.sh b/docker-build-runner.sh
index 9727f38..32f0267 100755
--- a/docker-build-runner.sh
+++ b/docker-build-runner.sh
@@ -12,6 +12,12 @@
 # Per-build step logs: $OUT_DIR/docker-build.log, $OUT_DIR/docker-run.log (also echoed to build.log).
 set -euo pipefail
 
+# PHP-FPM on Alpine often runs as nobody (HOME=/). Docker CLI needs a writable config dir.
+BUILDER_HOME="${BUILDER_HOME:-/var/www/ac/broadcast}"
+export HOME="${HOME:-${BUILDER_HOME}}"
+export DOCKER_CONFIG="${DOCKER_CONFIG:-${HOME}/.docker}"
+mkdir -p "${DOCKER_CONFIG}" 2>/dev/null || true
+
 ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 SCRIPTS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 IMAGE="${ANDROIDCAST_CI_IMAGE:-androidcast-ci:latest}"