diff --git a/src/columns/ColDate.h b/src/columns/ColDate.h
index d3c034d88..a79d7a7ea 100644
--- a/src/columns/ColDate.h
+++ b/src/columns/ColDate.h
@@ -37,7 +37,7 @@ class ColumnDate : public Column
 {
 public:
   ColumnDate ();
-  ~ColumnDate ();
+  virtual ~ColumnDate ();
 
   virtual bool validate (std::string&);
   virtual void measure (Task&, unsigned int&, unsigned int&);