diff --git a/dlls/mshtml/protocol.c b/dlls/mshtml/protocol.c
index 4304740281a..d9a008c87c2 100644
--- a/dlls/mshtml/protocol.c
+++ b/dlls/mshtml/protocol.c
@@ -478,6 +478,9 @@ static HRESULT WINAPI AboutProtocolInfo_QueryInfo(IInternetProtocolInfo *iface,
     case QUERY_USES_HISTORYFOLDER:
         FIXME("Unsupported option QUERY_USES_HISTORYFOLDER\n");
         return E_FAIL;
+    case QUERY_IS_CACHED_AND_USABLE_OFFLINE:
+        FIXME("Unsupported option QUERY_IS_CACHED_AND_USABLE_OFFLINE\n");
+        return E_NOTIMPL;
     default:
         return E_FAIL;
     }
diff --git a/dlls/mshtml/tests/protocol.c b/dlls/mshtml/tests/protocol.c
index 07f424fde74..5825015093f 100644
--- a/dlls/mshtml/tests/protocol.c
+++ b/dlls/mshtml/tests/protocol.c
@@ -755,6 +755,7 @@ static void test_about_protocol(void)
             case QUERY_IS_SECURE:
             case QUERY_IS_SAFE:
             case QUERY_USES_HISTORYFOLDER:
+            case QUERY_IS_CACHED_AND_USABLE_OFFLINE:
                 break;
             default:
                 hres = IInternetProtocolInfo_QueryInfo(protocol_info, about_blank_url, i, 0,
diff --git a/include/urlmon.idl b/include/urlmon.idl
index a9d07919e32..a278be5dbf4 100644
--- a/include/urlmon.idl
+++ b/include/urlmon.idl
@@ -881,7 +881,8 @@ interface IInternetProtocolInfo : IUnknown
         QUERY_USES_CACHE,
         QUERY_IS_SECURE,
         QUERY_IS_SAFE,
-        QUERY_USES_HISTORYFOLDER
+        QUERY_USES_HISTORYFOLDER,
+        QUERY_IS_CACHED_AND_USABLE_OFFLINE
     } QUERYOPTION;
 
     HRESULT ParseUrl(