diff --git a/dlls/mshtml/mshtml_private.h b/dlls/mshtml/mshtml_private.h
index 374b6c0059a..b19dbfa1261 100644
--- a/dlls/mshtml/mshtml_private.h
+++ b/dlls/mshtml/mshtml_private.h
@@ -38,6 +38,7 @@
 #define NS_ERROR_FAILURE          ((nsresult)0x80004005L)
 #define NS_NOINTERFACE            ((nsresult)0x80004002L)
 #define NS_ERROR_NOT_IMPLEMENTED  ((nsresult)0x80004001L)
+#define NS_ERROR_NOT_AVAILABLE    ((nsresult)0x80040111L)
 #define NS_ERROR_INVALID_ARG      ((nsresult)0x80070057L) 
 #define NS_ERROR_UNEXPECTED       ((nsresult)0x8000ffffL)
 #define NS_ERROR_UNKNOWN_PROTOCOL ((nsresult)0x804b0012L)
diff --git a/dlls/mshtml/nsio.c b/dlls/mshtml/nsio.c
index eb7aa73a495..8967fa13a77 100644
--- a/dlls/mshtml/nsio.c
+++ b/dlls/mshtml/nsio.c
@@ -1052,9 +1052,14 @@ static nsresult NSAPI nsChannel_GetRequestSucceeded(nsIHttpChannel *iface,
 {
     nsChannel *This = NSCHANNEL_THIS(iface);
 
-    FIXME("(%p)->(%p)\n", This, aRequestSucceeded);
+    TRACE("(%p)->(%p)\n", This, aRequestSucceeded);
 
-    return NS_ERROR_NOT_IMPLEMENTED;
+    if(!This->response_status)
+        return NS_ERROR_NOT_AVAILABLE;
+
+    *aRequestSucceeded = (This->response_status < 400);
+
+    return NS_OK;
 }
 
 static nsresult NSAPI nsChannel_GetResponseHeader(nsIHttpChannel *iface,