diff --git a/test/tap/debug-logs.js b/test/tap/debug-logs.js
index 8eb6c78049ea5..0e951c4bb082b 100644
--- a/test/tap/debug-logs.js
+++ b/test/tap/debug-logs.js
@@ -66,16 +66,28 @@ test('example', function (t) {
       t.matches(path.relative(cachedir, logfile), /^_logs/, 'debug log is inside the cache in _logs')
     }
 
-    // we run a bunch concurrently, this will actually create > than our limit as the check is done
-    // when the command starts
-    var todo = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
+    // we run a bunch concurrently, this will actually create > than our limit
+    // as the check is done when the command starts
+    //
+    // It has to be > the log count (10) but also significantly higher than
+    // the number of cores on the machine, or else some might be able to get
+    // to the log folder pruning logic in parallel, resulting in FEWER files
+    // than we expect being present at the end.
+    var procCount = Math.max(require('os').cpus().length * 2, 12)
+    var todo = new Array(procCount).join(',').split(',').map((v, k) => k)
     asyncMap(todo, function (num, next) {
+      // another way would be to just simulate this?
+      // var f = path.join(cachedir, '_logs', num + '-debug.log')
+      // require('fs').writeFile(f, 'log ' + num, next)
       common.npm(['run', '--logs-max=10', 'false'], conf, function (err, code) {
         if (err) throw err
         t.is(code, 1, 'run #' + num + ' errored as expected')
         next()
       })
     }, function () {
+      var files = glob.sync(path.join(cachedir, '_logs', '*'))
+      t.ok(files.length > 10, 'there should be more than 10 log files')
+
       // now we do one more and that should clean up the list
       common.npm(['run', '--logs-max=10', 'false'], conf, function (err, code) {
         if (err) throw err