diff --git a/common/JackThreadedDriver.cpp b/common/JackThreadedDriver.cpp
index ca8dde69..590d9575 100644
--- a/common/JackThreadedDriver.cpp
+++ b/common/JackThreadedDriver.cpp
@@ -209,6 +209,7 @@ bool JackThreadedDriver::Init()
         if (fDriver->IsRealTime()) {
             jack_log("JackThreadedDriver::Init IsRealTime");
             // Will do "something" on OSX only...
+            GetEngineControl()->fPeriod = GetEngineControl()->fConstraint = GetEngineControl()->fPeriodUsecs * 1000;
             fThread.SetParams(GetEngineControl()->fPeriod, GetEngineControl()->fComputation, GetEngineControl()->fConstraint);
             if (fThread.AcquireRealTime(GetEngineControl()->fServerPriority) < 0) {
                 jack_error("AcquireRealTime error");
diff --git a/common/JackWaitThreadedDriver.cpp b/common/JackWaitThreadedDriver.cpp
index 04529f02..7d0eee73 100644
--- a/common/JackWaitThreadedDriver.cpp
+++ b/common/JackWaitThreadedDriver.cpp
@@ -46,6 +46,7 @@ bool JackWaitThreadedDriver::Execute()
         if (fDriver->IsRealTime()) {
             jack_log("JackWaitThreadedDriver::Init IsRealTime");
             // Will do "something" on OSX only...
+            GetEngineControl()->fPeriod = GetEngineControl()->fConstraint = GetEngineControl()->fPeriodUsecs * 1000;
             fThread.SetParams(GetEngineControl()->fPeriod, GetEngineControl()->fComputation, GetEngineControl()->fConstraint);
             if (fThread.AcquireRealTime(GetEngineControl()->fServerPriority) < 0) {
                 jack_error("AcquireRealTime error");