diff --git a/storage/tianmu/util/bitset.h b/storage/tianmu/util/bitset.h
index 9a08e1d8bb..34f7b539f2 100644
--- a/storage/tianmu/util/bitset.h
+++ b/storage/tianmu/util/bitset.h
@@ -18,6 +18,7 @@
 #define TIANMU_UTIL_BITSET_H_
 #pragma once
 
+#include <string.h>
 namespace Tianmu {
 namespace utils {
 
@@ -32,6 +33,7 @@ class BitSet {
       ptr_ = new char[(sz + NO_OF_BITS - 1) / NO_OF_BITS]();
       allocated_ = true;
     }
+    memset(ptr_, 0, (sz + NO_OF_BITS - 1) / NO_OF_BITS);
   }
 
   ~BitSet() {
@@ -50,6 +52,7 @@ class BitSet {
       ptr_ = new char[(sz + NO_OF_BITS - 1) / NO_OF_BITS]();
       allocated_ = true;
     }
+    memset(ptr_, 0, (sz + NO_OF_BITS - 1) / NO_OF_BITS);
   }
 
   bool operator[](size_t pos) const { return ptr_[pos / NO_OF_BITS] & (1U << (pos % NO_OF_BITS)); }