diff --git a/io/io/test/TBufferMerger.cxx b/io/io/test/TBufferMerger.cxx
index 284fab88ce790912fccf4922ed1d297768b7a6f0..4707fa987f7dd167695adcbc86b901f461517ba7 100644
--- a/io/io/test/TBufferMerger.cxx
+++ b/io/io/test/TBufferMerger.cxx
@@ -341,12 +341,12 @@ TEST(TBufferMerger, RegisterCallbackTasks)
 
       TTaskGroup tg;
 
-      /* callback: launch up to two new tasks when called */
+      /* callback: launches new tasks when called */
       merger.RegisterCallback([&]() {
          int i = 0;
          while (launched < tasks && ++i <= 2) {
-            ++launched;
             tg.Run(task);
+            ++launched;
          }
       });