diff --git a/programs/dxdiag/main.c b/programs/dxdiag/main.c
index f57eec99292..b6ea5306d06 100644
--- a/programs/dxdiag/main.c
+++ b/programs/dxdiag/main.c
@@ -159,6 +159,12 @@ static BOOL process_command_line(const WCHAR *cmdline, struct command_line_info
 
             break;
 
+        case '6':
+            if (wcsnicmp(cmdline, L"64bit", 5))
+                return FALSE;
+            cmdline += 5;
+            break;
+
         case 'd':
         case 'D':
             if (wcsnicmp(cmdline, L"dontskip", 8))