diff --git a/pyext/ctobssim.i b/pyext/ctobssim.i
index f96c074..af90a4c 100644
--- a/pyext/ctobssim.i
+++ b/pyext/ctobssim.i
@@ -37,6 +37,7 @@ public:
 
     // Methods
     void           clear(void);
+    void           execute(void);
     void           run(void);
     void           save(void);
     GObservations& obs(void);