diff --git a/src/watchman/WatchmanBackend.cc b/src/watchman/WatchmanBackend.cc
index 04640037..6044c85f 100644
--- a/src/watchman/WatchmanBackend.cc
+++ b/src/watchman/WatchmanBackend.cc
@@ -1,6 +1,7 @@
 #include <string>
 #include <fstream>
 #include <stdlib.h>
+#include <filesystem>
 #include <algorithm>
 #include "../DirTree.hh"
 #include "../Event.hh"
@@ -241,8 +242,16 @@ void WatchmanBackend::writeSnapshot(Watcher &watcher, std::string *snapshotPath)
   std::unique_lock<std::mutex> lock(mMutex);
   watchmanWatch(watcher.mDir);
 
-  std::ofstream ofs(*snapshotPath);
-  ofs << clock(watcher);
+  auto clockValue = clock(watcher);
+  auto temporaryDirectory = std::filesystem::temp_directory_path();
+  auto temporaryFilePath = temporaryDirectory.append("tmp-parcel-snapshot.txt");
+  {
+    std::ofstream ofs(temporaryFilePath);
+    ofs << clockValue;
+    ofs.flush();
+    ofs.close();
+  }
+  std::filesystem::rename(temporaryFilePath, *snapshotPath);
 }
 
 void WatchmanBackend::getEventsSince(Watcher &watcher, std::string *snapshotPath) {
diff --git a/test/since.js b/test/since.js
index c3db9990..0cccee79 100644
--- a/test/since.js
+++ b/test/since.js
@@ -68,7 +68,7 @@ describe('since', () => {
 
       describe('files', () => {
         it('should emit when a file is created', async function () {
-          this.timeout(5000);
+          this.timeout(10000);
           let f = getFilename();
           await watcher.writeSnapshot(tmpDir, snapshotPath, {backend});
           if (isSecondPrecision) {