diff --git a/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.c b/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.c
index 66306e81dd..2f8274785c 100644
--- a/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.c
+++ b/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.c
@@ -17,6 +17,8 @@
 #define LOG_TAG "drv.pwm"
 #include <drv_log.h>
 
+#define ITEM_NUM(items) sizeof(items) / sizeof(items[0])
+
 void ch32_tim_clock_init(TIM_TypeDef* timx)
 {
 #ifdef BSP_USING_TIM1_PWM
diff --git a/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.h b/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.h
index d9c5ef4d4a..3b7f7c1c11 100644
--- a/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.h
+++ b/bsp/wch/risc-v/Libraries/ch32_drivers/drv_pwm.h
@@ -18,10 +18,6 @@
 #include <drivers/hwtimer.h>
 #include <board.h>
 
-#ifndef ITEM_NUM
-#define ITEM_NUM(items) sizeof(items) / sizeof(items[0])
-#endif
-
 #define MAX_COUNTER     65535
 #define MIN_COUNTER     2
 #define MIN_PULSE       2