diff --git a/Dockerfile b/Dockerfile
index 78a3cd9..5cec54d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -8,6 +8,7 @@ ARG CORS_ALLOWED_HEADERS=*
 ARG CORS_ALLOW_CREDENTIALS=false
 
 # Environment variables
+ENV TOMCAT_VERSION=$TOMCAT_VERSION
 ENV CATALINA_HOME=/opt/apache-tomcat-${TOMCAT_VERSION}
 ENV EXTRA_JAVA_OPTS="-Xms256m -Xmx1g"
 ENV CORS_ENABLED=$CORS_ENABLED