diff --git a/tools/osbuilder/rootfs-builder/rootfs.sh b/tools/osbuilder/rootfs-builder/rootfs.sh
index b63567ad5d..44fdab42ea 100755
--- a/tools/osbuilder/rootfs-builder/rootfs.sh
+++ b/tools/osbuilder/rootfs-builder/rootfs.sh
@@ -373,6 +373,8 @@ build_rootfs_distro()
 
 		docker_run_args=""
 		docker_run_args+=" --rm"
+		# apt sync scans all possible fds in order to close them, incredibly slow on VMs
+		docker_run_args+=" --ulimit nofile=262144:262144"
 		docker_run_args+=" --runtime ${DOCKER_RUNTIME}"
 
 		if [ -z "${AGENT_SOURCE_BIN}" ] ; then