diff --git a/mozilla/netwerk/protocol/http/src/nsHTTPHandler.cpp b/mozilla/netwerk/protocol/http/src/nsHTTPHandler.cpp
index 58d18dfb140..b764a59ea80 100644
--- a/mozilla/netwerk/protocol/http/src/nsHTTPHandler.cpp
+++ b/mozilla/netwerk/protocol/http/src/nsHTTPHandler.cpp
@@ -774,6 +774,8 @@ nsHTTPHandler::Init()
                 HTTPPrefsCallback, (void*)this);
     mPrefs->RegisterCallback(INTL_ACCEPT_LANGUAGES, 
                 HTTPPrefsCallback, (void*)this);
+    mPrefs->RegisterCallback(UA_PREF_PREFIX "override", 
+                HTTPPrefsCallback, (void*)this);
     mPrefs->RegisterCallback(UA_PREF_PREFIX "locale", 
                 HTTPPrefsCallback, (void*)this);
     mPrefs->RegisterCallback(UA_PREF_PREFIX "misc",
@@ -844,6 +846,8 @@ nsHTTPHandler::~nsHTTPHandler()
                 HTTPPrefsCallback, (void*)this);
         mPrefs->UnregisterCallback(INTL_ACCEPT_LANGUAGES, 
                 HTTPPrefsCallback, (void*)this);
+        mPrefs->UnregisterCallback(UA_PREF_PREFIX "override", 
+                HTTPPrefsCallback, (void*)this);
         mPrefs->UnregisterCallback(UA_PREF_PREFIX "locale", 
                 HTTPPrefsCallback, (void*)this);
         mPrefs->UnregisterCallback(UA_PREF_PREFIX "misc",
@@ -1467,6 +1471,19 @@ nsHTTPHandler::PrefsChanged(const char* pref)
 #endif
     }
 
+    // general.useragent.override
+    if ((bChangedAll) || !PL_strcmp(pref, UA_PREF_PREFIX "override")) {
+        nsXPIDLCString uval;
+        nsresult rv = NS_OK;
+        rv = mPrefs->CopyCharPref(UA_PREF_PREFIX "override",
+                                  getter_Copies(uval));
+        if (NS_SUCCEEDED(rv)) {
+            mAppUserAgentOverride.Assign(uval);
+            // rebuild the user agent
+            BuildUserAgent();
+        }
+    }
+
     if ( (bChangedAll)|| !PL_strcmp(pref, UA_PREF_PREFIX "locale") ) {// general.useragent.locale
         // 55156: re-Gather locale.
         nsXPIDLString uval;