diff --git a/run-document-server.sh b/run-document-server.sh
index 35e31f5..c8dcf39 100755
--- a/run-document-server.sh
+++ b/run-document-server.sh
@@ -410,11 +410,13 @@ update_welcome_page() {
   WELCOME_PAGE="${APP_DIR}-example/welcome/docker.html"
   if [[ -e $WELCOME_PAGE ]]; then
     DOCKER_CONTAINER_ID=$(basename $(cat /proc/1/cpuset))
-    if [[ -x $(command -v docker) ]]; then
-      DOCKER_CONTAINER_NAME=$(docker inspect --format="{{.Name}}" $DOCKER_CONTAINER_ID)
-      sed 's/$(sudo docker ps -q)/'"${DOCKER_CONTAINER_NAME#/}"'/' -i $WELCOME_PAGE
-    else
-      sed 's/$(sudo docker ps -q)/'"${DOCKER_CONTAINER_ID::12}"'/' -i $WELCOME_PAGE
+    if (( ${#DOCKER_CONTAINER_ID} >= 12 )); then
+      if [[ -x $(command -v docker) ]]; then
+        DOCKER_CONTAINER_NAME=$(docker inspect --format="{{.Name}}" $DOCKER_CONTAINER_ID)
+        sed 's/$(sudo docker ps -q)/'"${DOCKER_CONTAINER_NAME#/}"'/' -i $WELCOME_PAGE
+      else
+        sed 's/$(sudo docker ps -q)/'"${DOCKER_CONTAINER_ID::12}"'/' -i $WELCOME_PAGE
+      fi
     fi
   fi
 }