diff --git a/{{cookiecutter.git_repo_name}}/Dockerfile b/{{cookiecutter.git_repo_name}}/Dockerfile
index a32d740..29cd0d5 100644
--- a/{{cookiecutter.git_repo_name}}/Dockerfile
+++ b/{{cookiecutter.git_repo_name}}/Dockerfile
@@ -8,7 +8,8 @@ ARG GROUP_ID
 ### install dpkgs
 COPY dpkg-dependencies.txt /tmp/
 # hadolint ignore=SC2046
-RUN apt-get install -y --no-install-recommends --allow-unauthenticated $(grep "^[A-Za-z]" /tmp/dpkg-dependencies.txt | perl -nE 'print s/^([^#]+)[ ]+#.*/\1/gr') && \
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends --allow-unauthenticated $(grep "^[A-Za-z]" /tmp/dpkg-dependencies.txt | perl -nE 'print s/^([^#]+)[ ]+#.*/\1/gr') && \
     apt-get clean
 
 ### create new user account ('docker')