diff --git a/Dockerfile b/Dockerfile
index 781e55c2f..5af326bb3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -51,7 +51,9 @@ RUN /opt/guacamole/bin/build-guacamole.sh "$BUILD_DIR" /opt/guacamole "$BUILD_PR
 FROM tomcat:${TOMCAT_VERSION}-${TOMCAT_JRE}
 
 # Install XMLStarlet for server.xml alterations
-RUN apt-get update -qq && apt-get install -y xmlstarlet
+RUN apt-get update -qq \
+    && apt-get install -y xmlstarlet \
+    && rm -rf /var/lib/apt/lists/*
 
 # This is where the build artifacts go in the runtime image
 WORKDIR /opt/guacamole