diff --git a/selfMonitor.cpp b/selfMonitor.cpp
index 4df37f2..b752417 100644
--- a/selfMonitor.cpp
+++ b/selfMonitor.cpp
@@ -17,7 +17,10 @@ void saveData(){
     if(fp!=NULL){
         time_t timeNow = time(0);
         tm *curTime = localtime(&timeNow);
-        if(curTime->tm_hour<4) curTime = localtime(&timeNow-86400);
+        if(curTime->tm_hour<4){
+            timeNow -= 86400;
+            curTime = localtime(&timeNow);
+        }
         fprintf(fp, "%d %d %d %d", blackListTimeCount,curTime->tm_year,curTime->tm_mon,curTime->tm_mday);
         fclose(fp);
     }
@@ -46,7 +49,10 @@ int main(){
         fscanf(fp, "%d%d%d%d", &blackListTimeCount,&curYear,&curMonth,&curDay);
         time_t timeNow = time(0);
         tm *curTime = localtime(&timeNow);
-        if(curTime->tm_hour<4) curTime = localtime(&timeNow-86400);
+        if(curTime->tm_hour<4){
+            timeNow -= 86400;
+            curTime = localtime(&timeNow);
+        }
         if(curTime->tm_year!=curYear||curTime->tm_mon!=curMonth||curTime->tm_mday!=curDay){
             blackListTimeCount = 0;
         }