diff --git a/.gitignore b/.gitignore
index f0eca7899..a7186c072 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@
 .env
 .venv
 *.egg-info
+*.mo
 *.pyc
 *.sqlite3
 build
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d16f101a0..004a621de 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -23,6 +23,8 @@ database before running bootstrap or `make migrate` and `make test` will fail.
 # to get mysql client to install
 # export LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib"
 make bootstrap
+# If you update locale .po files, compile messages before running/testing
+make compilemessages
 # If you want to enable DEBUG (and development mode)
 echo 1 > ~/.config/promgen/DEBUG
 
diff --git a/Dockerfile b/Dockerfile
index 8359f53c5..89915035e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -47,6 +47,10 @@ COPY promgen/tests/examples/promgen.yml /etc/promgen/promgen.yml
 
 WORKDIR /usr/src/app
 RUN pip install --no-cache-dir -e .
+RUN set -ex \
+    && apk add --no-cache gettext \
+    && SECRET_KEY=1 promgen compilemessages \
+    && apk del gettext
 
 USER promgen
 EXPOSE 8000
diff --git a/Makefile b/Makefile
index 20d332ada..1ea5b5944 100644
--- a/Makefile
+++ b/Makefile
@@ -122,6 +122,11 @@ ruff-check-format: $(RUFF_BIN)
 migrate: $(APP_BIN)
 	$(APP_BIN) migrate
 
+.PHONY: compilemessages
+## Django: Compile locale messages (.po -> .mo)
+compilemessages: $(APP_BIN)
+	$(APP_BIN) compilemessages
+
 .PHONY:	run
 ## Django: Run development server
 run: migrate
diff --git a/promgen/locale/ja/LC_MESSAGES/django.mo b/promgen/locale/ja/LC_MESSAGES/django.mo
deleted file mode 100644
index 49cf7aed4..000000000
Binary files a/promgen/locale/ja/LC_MESSAGES/django.mo and /dev/null differ