diff --git a/src/history.h b/src/history.h
index bbac3903..0459c8fb 100644
--- a/src/history.h
+++ b/src/history.h
@@ -38,7 +38,6 @@
 class History {
 
 public:
-  History() { clear(); }
   void clear();
   Value value(Piece p, Square to) const;
   void update(Piece p, Square to, Value bonus);
diff --git a/src/tt.h b/src/tt.h
index c37b9d3f..5c3ddc52 100644
--- a/src/tt.h
+++ b/src/tt.h
@@ -56,7 +56,7 @@ public:
     memset(entries, 0, HashSize * sizeof(Entry));
   }
 
-  ~SimpleHash() { delete [] entries; }
+  virtual ~SimpleHash() { delete [] entries; }
 
   Entry* find(Key key) const { return entries + ((uint32_t)key & (HashSize - 1)); }