diff --git a/test/testmonpipe.cpp b/test/testmonpipe.cpp
index 7bf493c..7e3af8c 100644
--- a/test/testmonpipe.cpp
+++ b/test/testmonpipe.cpp
@@ -97,7 +97,8 @@ struct Spammer : public server::Source {
     }
 };
 
-void testSpam(uint32_t nQueue, uint32_t highMark, uint16_t lastVal)
+void testSpam(uint32_t nQueue, uint32_t highMark, uint16_t lastVal,
+              const std::string& ackAny="")
 {
     testShow()<<__func__<<" nQueue="<<nQueue<<" highMark="<<highMark<<" lastVal="<<lastVal;
 
@@ -110,17 +111,23 @@ void testSpam(uint32_t nQueue, uint32_t highMark, uint16_t lastVal)
     auto cli(srv.clientConfig().build());
 
     epicsEvent wait;
-    auto mon(cli.monitor("spam")
-             .record("highMark", highMark)
-             .record("queueSize", nQueue)
-             .record("lastVal", lastVal)
-             .record("pipeline", true)
-             .maskConnected(true)
-             .maskDisconnected(true)
-             .event([&wait](client::Subscription&){
-                 wait.signal();
-             })
-             .exec());
+    std::shared_ptr<client::Subscription> mon;
+    {
+        auto b(cli.monitor("spam")
+                   .record("highMark", highMark)
+                   .record("queueSize", nQueue)
+                   .record("lastVal", lastVal)
+                   .record("pipeline", true)
+                   .maskConnected(true)
+                   .maskDisconnected(true)
+                   .event([&wait](client::Subscription&){
+                       wait.signal();
+                   }));
+        if(!ackAny.empty()) {
+            b.record("ackAny", ackAny);
+        }
+        mon = b.exec();
+    }
 
     uint16_t expected = 0u;
     while(true) {
@@ -145,7 +152,7 @@ void testSpam(uint32_t nQueue, uint32_t highMark, uint16_t lastVal)
 
 MAIN(testmonpipe)
 {
-    testPlan(99);
+    testPlan(111);
     testSetup();
     logger_config_env();
     testSpam(3u, 0u, 7u);
@@ -157,6 +164,7 @@ MAIN(testmonpipe)
     testSpam(4u, 3u, 10u);
     testSpam(4u, 4u, 10u);
     testSpam(4u, 6u, 10u);
+    testSpam(4u, 6u, 10u, "50%");
     logger_config_env();
     cleanup_for_valgrind();
     return testDone();