diff --git a/modules/libpref/test/unit/test_libPrefs.js b/modules/libpref/test/unit/test_libPrefs.js
index e7fd5ca023f5..261ecbaf7798 100644
--- a/modules/libpref/test/unit/test_libPrefs.js
+++ b/modules/libpref/test/unit/test_libPrefs.js
@@ -359,6 +359,8 @@ function run_test() {
 
   // loading our former savePrefFile should allow us to read former prefs
   ps.readUserPrefs(savePrefFile);
+  // cleanup the file now we don't need it
+  savePrefFile.remove(false);
   do_check_eq(ps.getBoolPref("ReadPref.bool"), true);
   do_check_eq(ps.getIntPref("ReadPref.int"), 230);
   do_check_eq(ps.getCharPref("ReadPref.char"), "hello");