diff --git a/src/Statistics.h b/src/Statistics.h
index 9693a362..fc48ac7b 100644
--- a/src/Statistics.h
+++ b/src/Statistics.h
@@ -151,7 +151,7 @@ class ShareStatsDay {
   double earn1d_ = 0;
 
   // mark which hour data has been modified: 23, 22, ...., 0
-  uint32_t modifyHoursFlag_;
+  uint32_t modifyHoursFlag_ = 0;
   mutex lock_;
   string rpcUrl_;