diff --git a/Src/GroupTree/FGroupTaskDepAlgorithm.hpp b/Src/GroupTree/FGroupTaskDepAlgorithm.hpp
index 66ae537e00c1bdc351d2e06b941eabc84aa2f942..d8b9ffd74c9c9b8ba3f601467fcc632c2e552f70 100644
--- a/Src/GroupTree/FGroupTaskDepAlgorithm.hpp
+++ b/Src/GroupTree/FGroupTaskDepAlgorithm.hpp
@@ -88,6 +88,8 @@ public:
                 if(operationsToProceed & FFmmL2L) downardPass();
 
                 if( operationsToProceed & FFmmL2P ) mergePass();
+
+                #pragma omp taskwait
             }
         }
     }