diff --git a/GVFS/GVFS.FunctionalTests/Tests/EnlistmentPerFixture/PrefetchVerbTests.cs b/GVFS/GVFS.FunctionalTests/Tests/EnlistmentPerFixture/PrefetchVerbTests.cs
index cb0a2a4a6..bcfa9cbd3 100644
--- a/GVFS/GVFS.FunctionalTests/Tests/EnlistmentPerFixture/PrefetchVerbTests.cs
+++ b/GVFS/GVFS.FunctionalTests/Tests/EnlistmentPerFixture/PrefetchVerbTests.cs
@@ -131,10 +131,13 @@ private void PostFetchJobShouldComplete()
             string objectDir = this.Enlistment.GetObjectRoot(this.fileSystem);
             string postFetchLock = Path.Combine(objectDir, "post-fetch.lock");
 
-            while (this.fileSystem.FileExists(postFetchLock))
+            // Wait first, to hopefully ensure the background thread has
+            // started before we check for the lock file.
+            do
             {
                 Thread.Sleep(500);
             }
+            while (this.fileSystem.FileExists(postFetchLock));
 
             ProcessResult midxResult = GitProcess.InvokeProcess(this.Enlistment.RepoRoot, "midx --read --pack-dir=\"" + objectDir + "/pack\"");
             midxResult.ExitCode.ShouldEqual(0);