diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 42076bb17..c3e55e481 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -527,7 +527,7 @@ jobs:
       fail-fast: false
       matrix:
         box:
-          - fedora/39-cloud-base
+          - fedora/40-cloud-base
           # We have to keep EL8 to test old glibc, cgroup, kernel, etc.
           # The image was changed from rockylinux/8 to almalinux/8,
           # as the former one no longer works:
diff --git a/Vagrantfile b/Vagrantfile
index 6aea6bb28..6eeb9db9a 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -17,7 +17,7 @@
 
 # Vagrantfile for Fedora and EL
 Vagrant.configure("2") do |config|
-  config.vm.box = ENV["BOX"] ? ENV["BOX"].split("@")[0] : "fedora/39-cloud-base"
+  config.vm.box = ENV["BOX"] ? ENV["BOX"].split("@")[0] : "fedora/40-cloud-base"
   # BOX_VERSION is deprecated. Use "BOX=<BOX>@<BOX_VERSION>".
   config.vm.box_version = ENV["BOX_VERSION"] || (ENV["BOX"].split("@")[1] if ENV["BOX"])