diff --git a/dlls/oledb32/convert.c b/dlls/oledb32/convert.c
index 5bad1055825..971e6d90a74 100644
--- a/dlls/oledb32/convert.c
+++ b/dlls/oledb32/convert.c
@@ -619,7 +619,7 @@ static HRESULT WINAPI convert_DataConvert(IDataConvert* iface,
         {
             WCHAR szBuff[39];
             const GUID *id = (const GUID *)src;
-            WCHAR format[] = {
+            static const WCHAR format[] = {
                 '{','%','0','8','X','-','%','0','4','X','-','%','0','4','X','-',
                 '%','0','2','X','%','0','2','X','-',
                 '%','0','2','X','%','0','2','X','%','0','2','X','%','0','2','X','%','0','2','X','%','0','2','X','}',0};