Index: test/Prefs.cpp
===================================================================
--- a/test/Prefs.cpp
+++ b/test/Prefs.cpp
@@ -151,7 +151,7 @@
   filterEngine->SetPref("patternsbackupinterval", jsEngine->NewValue(48));
   filterEngine->SetPref("subscriptions_autoupdate", jsEngine->NewValue(false));
 
-  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  std::this_thread::sleep_for(std::chrono::milliseconds(100)); // RACE
 
   ASSERT_FALSE(fileSystem->prefsContents.empty());
 
@@ -222,7 +222,7 @@
   ASSERT_TRUE(filterEngine->GetPref("suppress_first_run_page")->AsBool());
   filterEngine->SetPref("suppress_first_run_page", jsEngine->NewValue(false));
 
-  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  std::this_thread::sleep_for(std::chrono::milliseconds(100)); // RACE
 
   ASSERT_FALSE(fileSystem->prefsContents.empty());