diff --git a/examples/cpp_virtual_methods/Makefile b/examples/cpp_virtual_methods/Makefile
index 749b3b594dc1d8623b2309ce03d26a0a28b4a39b..1de1859a0f874b631ea12cc29990211004137c39 100644
--- a/examples/cpp_virtual_methods/Makefile
+++ b/examples/cpp_virtual_methods/Makefile
@@ -18,6 +18,7 @@ CFLAGS:= \
 	-I/usr/include/newlib \
 	-I$(CH32V003FUN) \
 	-nostdlib \
+	-DCH32V003 \
 	-I. -Wall
 
 CFLAGS+=-fno-rtti -DSTDOUT_UART -DCPLUSPLUS