diff --git a/src/clientmon.cpp b/src/clientmon.cpp
index 288f1ec..2e96993 100644
--- a/src/clientmon.cpp
+++ b/src/clientmon.cpp
@@ -782,7 +782,7 @@ std::shared_ptr<Subscription> MonitorBuilder::exec()
             try {
                 auto percent = parseTo<double>(sval.substr(0, sval.size()-1u));
                 if(percent>0.0 && percent<=100.0) {
-                    op->ackAt = uint32_t(percent * op->queueSize);
+                    op->ackAt = uint32_t(percent / 100.0 * op->queueSize);
                 } else {
                     throw std::invalid_argument("not in range (0%, 100%]");
                 }
diff --git a/src/servermon.cpp b/src/servermon.cpp
index 47c1a74..2a83926 100644
--- a/src/servermon.cpp
+++ b/src/servermon.cpp
@@ -561,7 +561,7 @@ void ServerConn::handle_MONITOR()
                     if(sval.size()>1 && sval.back()=='%') {
                         try {
                             auto percent = parseTo<double>(sval.substr(0, sval.size()-1u));
-                            op->ackAt = std::max(0.0, std::min(percent, 100.0)) * op->limit;
+                            op->ackAt = std::max(0.0, std::min(percent, 100.0)) / 100.0 * op->limit;
                         }catch(std::exception& e){
                             logRemote(ioid, Level::Crit,
                                       SB()<<"Unable to parse% "<<pvRequest.nameOf(ackAny)<<" : "<<sval<<" : "<<e.what());