--- a/modules/libpref/prefapi.cpp
+++ b/modules/libpref/prefapi.cpp
@@ -62,17 +62,17 @@ matchPrefEntry(const PLDHashEntryHdr* en
     if (prefEntry->key == key) return true;
 
     if (!prefEntry->key || !key) return false;
 
     const char *otherKey = reinterpret_cast<const char*>(key);
     return (strcmp(prefEntry->key, otherKey) == 0);
 }
 
-PLDHashTable*       gHashTable;
+PLDHashTable*       gHashTable = nullptr;
 static PLArenaPool  gPrefNameArena;
 
 static struct CallbackNode* gCallbacks = nullptr;
 static bool         gIsAnyPrefLocked = false;
 // These are only used during the call to pref_DoCallback
 static bool         gCallbacksInProgress = false;
 static bool         gShouldCleanupDeadNodes = false;
 
@@ -349,20 +349,20 @@ pref_savePrefs(PLDHashTable* aTable, uin
         nsAutoCString prefValue;
         nsAutoCString prefPrefix;
         prefPrefix.AssignLiteral("user_pref(\"");
 
         // where we're getting our pref from
         PrefValue* sourcePref;
 
         if (pref->prefFlags.HasUserValue() &&
-            (pref_ValueChanged(pref->defaultPref,
+            (!(pref->prefFlags.HasDefault()) ||
+             pref_ValueChanged(pref->defaultPref,
                                pref->userPref,
                                pref->prefFlags.GetPrefType()) ||
-             !(pref->prefFlags.HasDefault()) ||
              pref->prefFlags.HasStickyDefault())) {
             sourcePref = &pref->userPref;
         } else {
             // do not save default prefs that haven't changed
             continue;
         }
 
         // strings are in quotes!