diff --git a/ch32v003fun/ch32v003fun.mk b/ch32v003fun/ch32v003fun.mk
index 2b3b194faf1fcff63d705be1847d2d1762ac87aa..2e5d579c3d947727e14b4b993cba106d5b5f1e65 100644
--- a/ch32v003fun/ch32v003fun.mk
+++ b/ch32v003fun/ch32v003fun.mk
@@ -1,5 +1,5 @@
 
-PREFIX:=riscv64-unknown-elf
+PREFIX?=riscv64-unknown-elf
 
 CH32V003FUN?=../../ch32v003fun
 MINICHLINK?=../../minichlink