diff --git a/src/Mamba.Core.pas b/src/Mamba.Core.pas
index 26c760e..81c5837 100644
--- a/src/Mamba.Core.pas
+++ b/src/Mamba.Core.pas
@@ -1558,6 +1558,7 @@ destructor TAsync.Destroy();
 
 procedure TAsync.Clear();
 begin
+  WaitForAllToTerminate();
   FBusy.Clear();
   FQueue.Clear();
 end;