diff --git a/common/rfb/UserPasswdGetter.h b/common/rfb/UserPasswdGetter.h
index 18b0bae..aa72c1d 100644
--- a/common/rfb/UserPasswdGetter.h
+++ b/common/rfb/UserPasswdGetter.h
@@ -25,6 +25,8 @@
     // case no user name will be retrieved.  The caller MUST delete [] the
     // result(s).
     virtual void getUserPasswd(char** user, char** password)=0;
+
+    virtual ~UserPasswdGetter() {}
   };
 }
 #endif