diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 394c6f25d..819704cf9 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -569,6 +569,7 @@ template <> struct IDMacroHelper<-1> {
 	}
 };
 
+#undef ID
 #define ID(_id) \
 		YOSYS_NAMESPACE_PREFIX IDMacroHelper< \
 				YOSYS_NAMESPACE_PREFIX lookup_well_known_id(#_id) \