diff --git a/dlls/gameux/gameexplorer.c b/dlls/gameux/gameexplorer.c
index 1690bd7339a..6bdb2e44596 100644
--- a/dlls/gameux/gameexplorer.c
+++ b/dlls/gameux/gameexplorer.c
@@ -35,9 +35,6 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(gameux);
 
-/* function from Shell32, not defined in header */
-extern BOOL WINAPI GUIDFromStringW(LPCWSTR psz, LPGUID pguid);
-
 /*******************************************************************************
  * GameUX helper functions
  */
@@ -780,7 +777,7 @@ HRESULT GAMEUX_FindGameInstanceId(
                     if(lstrcmpW(lpValue, sGDFBinaryPath)==0)
                     {
                         /* key found, let's copy instance id and exit */
-                        hr = (GUIDFromStringW(lpName, pInstanceId) ? S_OK : E_FAIL);
+                        hr = CLSIDFromString(lpName, pInstanceId);
                         found = TRUE;
                     }
                     HeapFree(GetProcessHeap(), 0, lpValue);
diff --git a/dlls/gameux/tests/gameexplorer.c b/dlls/gameux/tests/gameexplorer.c
index 5ed780c2a60..1f25f71a541 100644
--- a/dlls/gameux/tests/gameexplorer.c
+++ b/dlls/gameux/tests/gameexplorer.c
@@ -33,9 +33,6 @@
 
 #include "wine/test.h"
 
-/* function from Shell32, not defined in header */
-extern BOOL WINAPI GUIDFromStringW(LPCWSTR psz, LPGUID pguid);
-
 /*******************************************************************************
  * Pointers used instead of direct calls. These procedures are not available on
  * older system, which causes problem while loading test binary.
@@ -476,7 +473,7 @@ static void _findGameInstanceId(int line,
                     if(lstrcmpW(lpValue, sGDFBinaryPath)==0)
                     {
                         /* key found, let's copy instance id and exit */
-                        hr = (GUIDFromStringW(lpName, pInstanceId) ? S_OK : E_FAIL);
+                        hr = CLSIDFromString(lpName, pInstanceId);
                         ok(SUCCEEDED(hr), "cannot convert subkey to guid: %s\n",
                                wine_dbgstr_w(lpName));