diff --git a/src/gd32e23x_it.c b/src/gd32e23x_it.c
index acc74b7..0bfcec3 100644
--- a/src/gd32e23x_it.c
+++ b/src/gd32e23x_it.c
@@ -34,7 +34,7 @@ OF SUCH DAMAGE.
 
 #include "gd32e23x_it.h"
 
-__IO uint16_t g_capture_value;
+extern uint16_t g_capture_value;
 
 /*!
     \brief      this function handles NMI exception
diff --git a/src/main.c b/src/main.c
index 78a7a2c..023f270 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,9 +7,7 @@
 #include "main.h"
 
 volatile uint8_t g_temperature_uint8[2] = {0};
-
-extern uint16_t g_capture_value;
-uint16_t g_distance_uint16;
+volatile uint16_t g_capture_value;
 
 /*!
     \brief      main function