diff --git a/Vagrantfile b/Vagrantfile
index d9e56f1..4193194 100644
--- a/Vagrantfile
+++ b/Vagrantfile
@@ -38,9 +38,15 @@ Vagrant.configure("2") do |config|
         %[id -u #{longuser} &>/dev/null || useradd #{longuser}]
 
     test_dir = "/home/vagrant/testcases"
+    # Because the timestamps are formatted differently depending on whether
+    # they’re in the current year or not (see `details.rs`), we have to make
+    # sure that the files are created in the current year, so they get shown
+    # in the format we expect.
+    current_year = Date.today.year
+    some_date = "#{current_year}01011234.56"  # 1st January, 12:34:56
+
     invalid_uid = 666
     invalid_gid = 616
-    some_date = "201601011234.56"  # 1st January 2016, 12:34:56
 
     # Delete old testcases if they exist already.
     # This needs root because the generator does some sudo-ing.
diff --git a/xtests/run.sh b/xtests/run.sh
index 998852d..f6c8a12 100755
--- a/xtests/run.sh
+++ b/xtests/run.sh
@@ -12,6 +12,11 @@ testcases=~/testcases
 results=/vagrant/xtests
 
 
+# Check that no files were created more than a year ago.
+# Files not from the current year use a different date format, meaning
+# that tests will fail until the VM gets re-provisioned.
+sudo find $testcases -mtime +365 -printf "File %p has not been modified since %TY! Consider re-provisioning; tests will probably fail.\n"
+
 # Long view tests
 $exa $testcases/files -l   | diff -q - $results/files_l     || exit 1
 $exa $testcases/files -lh  | diff -q - $results/files_lh    || exit 1