diff --git a/mozilla/extensions/pref/system-pref/src/nsSystemPref.cpp b/mozilla/extensions/pref/system-pref/src/nsSystemPref.cpp
index 9dc9177d206..09045205bcb 100644
--- a/mozilla/extensions/pref/system-pref/src/nsSystemPref.cpp
+++ b/mozilla/extensions/pref/system-pref/src/nsSystemPref.cpp
@@ -60,6 +60,8 @@ struct SysPrefItem {
     SysPrefItem() {
         prefName = nsnull;
         defaultValue.intVal = 0;
+        defaultValue.stringVal = nsnull;
+        defaultValue.boolVal = PR_FALSE;
         isLocked = PR_FALSE;
     }
     void SetPrefName(const char *aPrefName) {