diff --git a/ecp5/arch.h b/ecp5/arch.h
index 131e06bd..19fe1c4d 100644
--- a/ecp5/arch.h
+++ b/ecp5/arch.h
@@ -539,7 +539,7 @@ struct Arch : BaseCtx
     BelRange getBelsByTile(int x, int y) const;
 
     bool getBelGlobalBuf(BelId bel) const { return getBelType(bel) == id_DCCA; }
-    bool getBelIOB(BelId bel) const { return chip_info->bel_data[bel.index].type == ID_TRELLIS_IO; }
+    bool getBelIOB(BelId bel) const { return getBelType(bel) == ID_TRELLIS_IO; }
 
     bool checkBelAvail(BelId bel) const
     {