diff --git a/run.sh b/run.sh
index b733664..509658b 100755
--- a/run.sh
+++ b/run.sh
@@ -141,7 +141,11 @@ while true; do
     docker system prune --all --force
   fi
   if [[ "${WEBAPP_IMAGE_PRUNE:-true}" == "true" ]]; then
-    docker image rm -f $(docker image ls --quiet --filter 'reference=laconic-webapp')
+    OLD_IMAGES="$(docker image ls --quiet --filter 'reference=laconic-webapp')"
+    if [[ -n "$OLD_IMAGES" ]]; then
+      echo "Pruning images: $OLD_IMAGES"
+      docker image rm -f $OLD_IMAGES
+    fi
   fi
   sleep ${CHECK_INTERVAL:-15}
 done