diff --git a/Dockerfile b/Dockerfile
index 5d6b6f9b..0d820eb1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,6 @@ FROM perl:5.40-bookworm
 
 ENV ANYEVENT_WEBSOCKET_TEST_SKIP_SSL=1
 
-COPY . /home/lacuna/server
 WORKDIR /home/lacuna/server
 
 # System libraries the XS dependencies link against (Debian package names).
@@ -32,12 +31,16 @@ RUN cpanm --notest Carton
 RUN cpanm --notest -l local --build-timeout=3600 --configure-timeout=1800 \
   Memcached::libmemcached@1.001801
 
+COPY ./cpanfile ./cpanfile.snapshot /home/lacuna/server
+
 # With a committed cpanfile.snapshot, install strictly from it (reproducible).
 # On the very first build (no snapshot yet), resolve freely and generate one —
 # extract it with `docker cp` and commit it, then all later builds are pinned.
 RUN carton install --deployment \
   && rm -rf /root/.cpanm /root/.perl-cpm
 
+COPY . /home/lacuna/server
+
 # Carton installs into ./local — put its binaries and libs on the default
 # search paths so `plackup` / `perl` in bin/startdev.sh and the compose
 # `command:` lines resolve without needing `carton exec`.