diff --git a/Dockerfile b/Dockerfile
index 0e3e7b86e25e078a211f6301e5b05bed901c1d39..19781b27577a458c340b6e629563a1b7a1ded47a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -11,7 +11,7 @@ LABEL \
     org.label-schema.vcs-url="https://gitlab.gwdg.de/dariah-de/textgridrep/repdav" \
     org.label-schema.vendor="SUB/FE"
 
-
+RUN apk add --no-cache g++ icu-dev
 RUN adduser -D repdav
 USER repdav
 
diff --git a/requirements.txt b/requirements.txt
index ebddd75963dab42c9c660b23b3d08f9cad298546..5b0f07c107a0ee41b365c53346c9983e6cd3a14b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,5 @@
-git+https://gitlab.gwdg.de/dariah-de/textgridrep/textgrid-python-clients.git@21-port-filename-for-textgrid-object-generation-from-link-rewriter
+# the 21-port-filename-for-textgrid-object-generation-from-link-rewriter branch:
+https://gitlab.gwdg.de/dariah-de/textgridrep/textgrid-python-clients/-/archive/21-port-filename-for-textgrid-object-generation-from-link-rewriter/textgrid-python-clients-21-port-filename-for-textgrid-object-generation-from-link-rewriter.tar.gz
 cheroot==8.5.2
 sentry-sdk==1.4.3
 WsgiDAV==4.0.1