diff --git a/test/case52/src/testcase52.c b/test/case52/src/testcase52.c
index 71ccddb..68b5def 100755
--- a/test/case52/src/testcase52.c
+++ b/test/case52/src/testcase52.c
@@ -70,7 +70,7 @@ uint8_t                                 w_idx, r_idx;   // RX 信号
 
 //----------------------------------------------------
 
-uint32_t slot_ind_flag = 0;
+volatile uint32_t slot_ind_flag = 0;
 uint32_t slot_ind_time_flag = 0;
 uint32_t g_slot_time = 0;
 uint32_t gu32_value = 0;