diff --git a/docker/PLA/Dockerfile b/docker/PLA/Dockerfile
index 712a095..8d4350b 100644
--- a/docker/PLA/Dockerfile
+++ b/docker/PLA/Dockerfile
@@ -46,7 +46,8 @@
 LABEL authors="Lars-Göran Magnusson"
 
 RUN DEBIAN_FRONTEND=noninteractive apt-get --yes update && \
-    DEBIAN_FRONTEND=noninteractive apt-get --yes install python3-minimal=3.6.*
+    DEBIAN_FRONTEND=noninteractive apt-get --yes install python3-minimal=3.6.* \
+    && rm -rf /var/lib/apt/lists/*
 
 COPY --from=INSTALL /usr/lib/python3/dist-packages /usr/lib/python3/dist-packages
 COPY --from=INSTALL /usr/local/lib/python3.6/dist-packages  /usr/local/lib/python3.6/dist-packages