diff --git a/crates/fbuild-config/assets/boards/json/genericCH32V303VCT6.json b/crates/fbuild-config/assets/boards/json/genericCH32V303VCT6.json
index cb8225ae..4c8a2981 100644
--- a/crates/fbuild-config/assets/boards/json/genericCH32V303VCT6.json
+++ b/crates/fbuild-config/assets/boards/json/genericCH32V303VCT6.json
@@ -8,7 +8,7 @@
     },
     "clock_source": "hsi+pll",
     "core": "openwch",
-    "extra_flags": "-DCH32V303VC -DCH32V30X -DCH32V30x -DCH32V303",
+    "extra_flags": "-DCH32V303VC -DCH32V30X -DCH32V30x -DCH32V303 -DCH32V30x_D8",
     "f_cpu": "144000000L",
     "mabi": "ilp32",
     "march": "rv32imacxw",