diff --git a/.docker/Dockerfile b/.docker/Dockerfile
index 4498822006a5cf427b24b833399ba54c95683cc2..0a7d2f0f2681c79ec57135ae850a6c3063a54635 100644
--- a/.docker/Dockerfile
+++ b/.docker/Dockerfile
@@ -18,16 +18,16 @@ RUN rm -rf .git
 
 RUN apt-get install -y openjdk-11-jdk-headless
 
-ENV CPPLIB_VERSION=$CPPLIB_VERSION
-RUN echo $CPPLIB_VERSION
+ENV ENV_CPPLIB_VERSION=$CPPLIB_VERSION
+RUN echo $ENV_CPPLIB_VERSION
 
 # build and run tests
 CMD ls -la && \
     ls -la /usr/local/lib/ && \
-    ls -la /usr/local/lib/libcaosdb-$CPPLIB_VERSION && \
+    ls -la /usr/local/lib/libcaosdb-${ENV_CPPLIB_VERSION} && \
     mkdir build && \
     cd build && \
     /wait-for-it.sh caosdb-server:10443 -t 500 -- \
-    cmake -D CMAKE_PREFIX_PATH=/usr/local/lib/libcaosdb-$CPPLIB_VERSION .. && \
+    cmake -D CMAKE_PREFIX_PATH=/usr/local/lib/libcaosdb-${ENV_CPPLIB_VERSION} .. && \
     cmake --build . && \
     ctest