diff --git a/bmi.hxx b/bmi.hxx
index d1c8348..f992681 100644
--- a/bmi.hxx
+++ b/bmi.hxx
@@ -19,6 +19,8 @@ namespace bmi {
 
   class Bmi {
     public:
+      virtual ~Bmi() { }
+
       // Model control functions.
       virtual void Initialize(std::string config_file) = 0;
       virtual void Update() = 0;