diff --git a/src/generic/Flush.cpp b/src/generic/Flush.cpp
index 66925216988f1ef0197ea22ea897bb156f3f8dac..1f1c7d65a11847d14e3db0dc3b3b9c15e10774de 100644
--- a/src/generic/Flush.cpp
+++ b/src/generic/Flush.cpp
@@ -67,7 +67,8 @@ public:
   }
   static void registerKeywords( Keywords& keys );
   void calculate(){}
-  void apply(){
+  void apply(){}
+  void update(){
     plumed.fflush();
     log.flush();
     const ActionSet & actionSet(plumed.getActionSet());