diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c23750d..5ba2103 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -24,7 +24,7 @@
     - apk add --no-cache git
   script:
     - docker build -f Dockerfile -t korap/kalamar:$VID-large --target kalamar .
-    - docker run  --rm -v /var/run/docker.sock:/var/run/docker.sock mintoolkit/mint --crt-api-version 1.46 build --http-probe=true --exec="perl Makefile.PL && MOJO_MODE=test make test && unzip -v" --include-workdir=true --include-path=/usr/local/share/perl5/site_perl/KorAP/ --include-path=/usr/local/share/perl5/site_perl/Mojolicious/ --include-path=/usr/local/share/perl5/site_perl/Mojo/ --tag korap/kalamar:$VID --tag korap/kalamar:latest korap/kalamar:$VID-large || true
+    - docker run  --rm -v /var/run/docker.sock:/var/run/docker.sock mintoolkit/mint --crt-api-version 1.46 build --http-probe=true --exec="perl Makefile.PL && MOJO_MODE=test make test && unzip -v" --include-workdir=true --include-path=/usr/local/share/perl5/site_perl/KorAP/ --include-path=/usr/local/share/perl5/site_perl/Mojolicious/ --include-path=/usr/local/share/perl5/site_perl/Mojo/ --include-path=/usr/share/perl5/vendor_perl/DateTime/ --include-path=/usr/share/perl5/vendor_perl/auto/share/dist/DateTime-Locale --include-path=/usr/share/perl5/core_perl/Unicode/Collate/Locale --tag korap/kalamar:$VID --tag korap/kalamar:latest korap/kalamar:$VID-large || true
     - ARTIFACT=kalamar-${VID}.tar.xz
     - docker save korap/kalamar:$VID | xz -T0 -M16G -9 > "$ARTIFACT"
   artifacts:
diff --git a/Changes b/Changes
index a6e8049..8d374cb 100644
--- a/Changes
+++ b/Changes
@@ -16,6 +16,7 @@
         - Update dependencies (diewald)
         - Support combined toggle+widget button for plugins (diewald)
         - Make KWIC metadata fields configurable by request URL (kupietz)
+        - Fix localization in slimming process (diewald; fixes #277)
 
 0.64 2026-02-14
         - Improve 'Plugins' mounting (diewald)
diff --git a/Dockerfile b/Dockerfile
index cec81c5..c4af265 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -82,9 +82,9 @@
 
 RUN mkdir /kalamar/data
 
-ENV MOJO_PORT   64543
-ENV MOJO_LISTEN http://*:${MOJO_PORT}
-ENV MOJO_MODE   production
+ENV MOJO_PORT=64543
+ENV MOJO_LISTEN=http://*:${MOJO_PORT}
+ENV MOJO_MODE=production
 
 RUN echo "{Kalamar=>{plugins=>['KorAPXML2Krill','Tei2KorAPXML','KorAPXML2CoNLLU','Plugins'],proxies=>['PROXY_STUB']},'Kalamar-Plugins'=>{default=>['PLUGIN_STUB']}}" > kalamar.production.conf
 
diff --git a/slim_script.sh b/slim_script.sh
index b726145..ca44aeb 100755
--- a/slim_script.sh
+++ b/slim_script.sh
@@ -14,6 +14,9 @@
            --include-path="/usr/local/share/perl5/site_perl/KorAP/" \
            --include-path="/usr/local/share/perl5/site_perl/Mojolicious/" \
            --include-path="/usr/local/share/perl5/site_perl/Mojo/" \
+           --include-path="/usr/share/perl5/vendor_perl/DateTime/" \
+           --include-path="/usr/share/perl5/vendor_perl/auto/share/dist/DateTime-Locale" \
+           --include-path="/usr/share/perl5/core_perl/Unicode/Collate/Locale" \
            --tag "korap/kalamar:$VERSION" \
            --tag "korap/kalamar:latest" \
            "korap/kalamar:${VERSION}-large"