diff --git a/dlls/hlink/extserv.c b/dlls/hlink/extserv.c
index daedf9eac74..c4e95abe5f3 100644
--- a/dlls/hlink/extserv.c
+++ b/dlls/hlink/extserv.c
@@ -26,9 +26,10 @@ WINE_DEFAULT_DEBUG_CHANNEL(hlink);
 #define DEFINE_THIS(cls,ifc,iface) ((cls*)((BYTE*)(iface)-offsetof(cls,lp ## ifc ## Vtbl)))
 
 typedef struct {
-    const IUnknownVtbl        *lpIUnknownVtbl;
-    const IAuthenticateVtbl   *lpIAuthenticateVtbl;
-    const IHttpNegotiateVtbl  *lpIHttpNegotiateVtbl;
+    const IUnknownVtbl              *lpIUnknownVtbl;
+    const IAuthenticateVtbl         *lpIAuthenticateVtbl;
+    const IHttpNegotiateVtbl        *lpIHttpNegotiateVtbl;
+    const IExtensionServicesVtbl    *lpIExtensionServicesVtbl;
 
     LONG ref;
     IUnknown *outer;
@@ -42,6 +43,7 @@ typedef struct {
 #define EXTSERVUNK(x)    ((IUnknown*)       &(x)->lpIUnknownVtbl)
 #define AUTHENTICATE(x)  ((IAuthenticate*)  &(x)->lpIAuthenticateVtbl)
 #define HTTPNEGOTIATE(x) ((IHttpNegotiate*) &(x)->lpIHttpNegotiateVtbl)
+#define EXTENSIONSERVICES(x) ((IExtensionServices*) &(x)->lpIExtensionServicesVtbl)
 
 #define EXTSERVUNK_THIS(iface)  DEFINE_THIS(ExtensionService, IUnknown, iface)
 
@@ -60,6 +62,9 @@ static HRESULT WINAPI ExtServUnk_QueryInterface(IUnknown *iface, REFIID riid, vo
     }else if(IsEqualGUID(&IID_IHttpNegotiate, riid)) {
         TRACE("(%p)->(IID_IHttpNegotiate %p)\n", This, ppv);
         *ppv = HTTPNEGOTIATE(This);
+    }else if(IsEqualGUID(&IID_IExtensionServices, riid)) {
+        TRACE("(%p)->(IID_IExtensionServices %p)\n", This, ppv);
+        *ppv = EXTENSIONSERVICES(This);
     }
 
     if(*ppv) {
@@ -209,6 +214,90 @@ static const IHttpNegotiateVtbl HttpNegotiateVtbl = {
     HttpNegotiate_OnResponse
 };
 
+#define EXTENSIONSERVICES_THIS(iface) DEFINE_THIS(ExtensionService, IExtensionServices, iface)
+
+static HRESULT WINAPI ExtServ_QueryInterface(IExtensionServices *iface, REFIID riid, void **ppv)
+{
+    ExtensionService *This = EXTENSIONSERVICES_THIS(iface);
+    return IUnknown_QueryInterface(This->outer, riid, ppv);
+}
+
+static ULONG WINAPI ExtServ_AddRef(IExtensionServices *iface)
+{
+    ExtensionService *This = EXTENSIONSERVICES_THIS(iface);
+    return IUnknown_AddRef(This->outer);
+}
+
+static ULONG WINAPI ExtServ_Release(IExtensionServices *iface)
+{
+    ExtensionService *This = EXTENSIONSERVICES_THIS(iface);
+    return IUnknown_Release(This->outer);
+}
+
+static HRESULT ExtServ_ImplSetAdditionalHeaders(ExtensionService* This, LPCWSTR pwzAdditionalHeaders)
+{
+    int len = 0;
+
+    heap_free(This->headers);
+    This->headers = NULL;
+
+    if (!pwzAdditionalHeaders)
+        return S_OK;
+
+    len = strlenW(pwzAdditionalHeaders);
+
+    if(len && pwzAdditionalHeaders[len-1] != '\n' && pwzAdditionalHeaders[len-1] != '\r') {
+        static const WCHAR endlW[] = {'\r','\n',0};
+        This->headers = heap_alloc(len*sizeof(WCHAR) + sizeof(endlW));
+        memcpy(This->headers, pwzAdditionalHeaders, len*sizeof(WCHAR));
+        memcpy(This->headers+len, endlW, sizeof(endlW));
+    }else {
+        This->headers = hlink_strdupW(pwzAdditionalHeaders);
+    }
+
+    return S_OK;
+}
+
+static HRESULT WINAPI ExtServ_SetAdditionalHeaders(IExtensionServices* iface, LPCWSTR pwzAdditionalHeaders)
+{
+    ExtensionService *This = EXTENSIONSERVICES_THIS(iface);
+
+    TRACE("(%p)->(%s)\n", This, debugstr_w(pwzAdditionalHeaders));
+
+    return ExtServ_ImplSetAdditionalHeaders(This,pwzAdditionalHeaders);
+}
+
+static HRESULT ExtServ_ImplSetAuthenticateData(ExtensionService* This, HWND phwnd, LPCWSTR pwzUsername, LPCWSTR pwzPassword)
+{
+    heap_free(This->username);
+    heap_free(This->password);
+
+    This->hwnd = phwnd;
+    This->username = hlink_strdupW(pwzUsername);
+    This->password = hlink_strdupW(pwzPassword);
+
+    return S_OK;
+}
+
+static HRESULT WINAPI ExtServ_SetAuthenticateData(IExtensionServices* iface, HWND phwnd, LPCWSTR pwzUsername, LPCWSTR pwzPassword)
+{
+    ExtensionService *This = EXTENSIONSERVICES_THIS(iface);
+
+    TRACE("(%p)->(%p %s %s)\n", This, phwnd, debugstr_w(pwzUsername), debugstr_w(pwzPassword));
+
+    return ExtServ_ImplSetAuthenticateData(This, phwnd, pwzUsername, pwzPassword);
+}
+
+#undef EXTENSIONSERVICES_THIS
+
+static const IExtensionServicesVtbl ExtServVtbl = {
+    ExtServ_QueryInterface,
+    ExtServ_AddRef,
+    ExtServ_Release,
+    ExtServ_SetAdditionalHeaders,
+    ExtServ_SetAuthenticateData
+};
+
 /***********************************************************************
  *             HlinkCreateExtensionServices (HLINK.@)
  */
@@ -217,7 +306,6 @@ HRESULT WINAPI HlinkCreateExtensionServices(LPCWSTR pwzAdditionalHeaders,
         IUnknown *punkOuter, REFIID riid, void** ppv)
 {
     ExtensionService *ret;
-    int len = 0;
     HRESULT hres = S_OK;
 
     TRACE("%s %p %s %s %p %s %p\n",debugstr_w(pwzAdditionalHeaders),
@@ -229,22 +317,15 @@ HRESULT WINAPI HlinkCreateExtensionServices(LPCWSTR pwzAdditionalHeaders,
     ret->lpIUnknownVtbl = &ExtServUnkVtbl;
     ret->lpIAuthenticateVtbl = &AuthenticateVtbl;
     ret->lpIHttpNegotiateVtbl = &HttpNegotiateVtbl;
+    ret->lpIExtensionServicesVtbl= &ExtServVtbl;
     ret->ref = 1;
-    ret->hwnd = phwnd;
-    ret->username = hlink_strdupW(pszUsername);
-    ret->password = hlink_strdupW(pszPassword);
+    ret->headers = NULL;
+    ret->hwnd = NULL;
+    ret->username = NULL;
+    ret->password = NULL;
 
-    if(pwzAdditionalHeaders)
-        len = strlenW(pwzAdditionalHeaders);
-
-    if(len && pwzAdditionalHeaders[len-1] != '\n' && pwzAdditionalHeaders[len-1] != '\r') {
-        static const WCHAR endlW[] = {'\r','\n',0};
-        ret->headers = heap_alloc(len*sizeof(WCHAR) + sizeof(endlW));
-        memcpy(ret->headers, pwzAdditionalHeaders, len*sizeof(WCHAR));
-        memcpy(ret->headers+len, endlW, sizeof(endlW));
-    }else {
-        ret->headers = hlink_strdupW(pwzAdditionalHeaders);
-    }
+    ExtServ_ImplSetAuthenticateData(ret, phwnd, pszUsername, pszPassword);
+    ExtServ_ImplSetAdditionalHeaders(ret, pwzAdditionalHeaders);
 
     if(!punkOuter) {
         ret->outer = EXTSERVUNK(ret);
diff --git a/include/hlguids.h b/include/hlguids.h
index 77bac3e4a94..7a45e668d86 100644
--- a/include/hlguids.h
+++ b/include/hlguids.h
@@ -25,5 +25,7 @@ DEFINE_GUID(CLSID_StdHlink,
     0x79eac9d0, 0xbaf9, 0x11ce, 0x8c, 0x82, 0x00, 0xaa,0x00,0x4b,0xa9,0x0b);
 DEFINE_GUID(CLSID_StdHlinkBrowseContext,
     0x79eac9d1, 0xbaf9, 0x11ce, 0x8c, 0x82, 0x00, 0xaa,0x00,0x4b,0xa9,0x0b);
+DEFINE_GUID(CLSID_IID_IExtensionServices,
+    0x79eac9cb, 0xbaf9, 0x11ce, 0x8c, 0x82, 0x00, 0xaa,0x00,0x4b,0xa9,0x0b);
 
 #endif
diff --git a/include/hlink.idl b/include/hlink.idl
index c59cd32098b..886acb36411 100644
--- a/include/hlink.idl
+++ b/include/hlink.idl
@@ -416,3 +416,25 @@ interface IHlinkFrame : IUnknown
         [in, unique] LPCWSTR pwzLocation, 
         [in, unique] LPCWSTR pwzFriendlyName);
 }
+
+/*****************************************************************************
+ *    IExtensionServices interface
+ */
+[
+    object,
+    uuid(79eac9cb-baf9-11ce-8c82-00aa004ba90b),
+    pointer_default(unique)
+]
+
+interface IExtensionServices: IUnknown
+{
+    typedef IExtensionServices *LPEXTENSIONSERVICES;
+
+    HRESULT SetAdditionalHeaders(
+        [in] LPCWSTR pwzAdditionalHeaders);
+
+    HRESULT SetAuthenticateData(
+        [in] HWND phwnd,
+        [in] LPCWSTR pwzUsername,
+        [in] LPCWSTR pwzPassword);
+}