diff --git a/kernel.spec.in b/kernel.spec.in
index fab3b381..7ce13eb5 100644
--- a/kernel.spec.in
+++ b/kernel.spec.in
@@ -607,6 +607,9 @@ if [ "$current_default_package" = "%{name}-qubes-vm" ]; then
 type qubes-prefs &>/dev/null && qubes-prefs --set default-kernel %upstream_version-%plainrel
 fi
 
+# make modules.img sparse (again)
+fallocate --dig-holes %vm_install_dir/modules.img
+
 exit 0
 
 %preun qubes-vm