diff --git a/rt-thread-version/rt-thread-standard/programming-manual/device/adc/adc.md b/rt-thread-version/rt-thread-standard/programming-manual/device/adc/adc.md
index 8d66cb18db4cb20ce5807d66e8f6363c97e67285..bd2cc4200442ee2b32a83716bf7da4f69e8c0a0d 100644
--- a/rt-thread-version/rt-thread-standard/programming-manual/device/adc/adc.md
+++ b/rt-thread-version/rt-thread-standard/programming-manual/device/adc/adc.md
@@ -117,7 +117,7 @@ rt_uint32_t rt_adc_read(rt_adc_device_t dev, rt_uint32_t channel);
 #define CONVERT_BITS        (1 << 12)   /* 转换位数为12位 */
 
 rt_adc_device_t adc_dev;            /* ADC 设备句柄 */
-rt_uint32_t value；
+rt_uint32_t value, vol;
 /* 查找设备 */
 adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);
 /* 使能设备 */