diff --git a/dlls/d3dxof/d3dxof.c b/dlls/d3dxof/d3dxof.c
index 20993f5628..a953573a3e 100644
--- a/dlls/d3dxof/d3dxof.c
+++ b/dlls/d3dxof/d3dxof.c
@@ -817,7 +817,7 @@ static WORD parse_TOKEN(parse_buffer * buf)
         break;
       case TOKEN_GUID:
         {
-          char strguid[38];
+          char strguid[39];
           GUID class_id;
 
           if (!read_bytes(buf, &class_id, 16))