diff --git a/common/JackMidiDriver.cpp b/common/JackMidiDriver.cpp
index b8993e7a..454f046d 100644
--- a/common/JackMidiDriver.cpp
+++ b/common/JackMidiDriver.cpp
@@ -74,9 +74,12 @@ int JackMidiDriver::Attach()
     jack_port_id_t port_index;
     char name[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
     char alias[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
+    jack_latency_range_t latency_range;
+    jack_nframes_t latency = fEngineControl->fBufferSize;
     int i;
 
     jack_log("JackMidiDriver::Attach fBufferSize = %ld fSampleRate = %ld", fEngineControl->fBufferSize, fEngineControl->fSampleRate);
+    latency_range.max = latency_range.min = latency;
 
     for (i = 0; i < fCaptureChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:out%d", fAliasName, fCaptureDriverName, i + 1);
@@ -87,10 +90,16 @@ int JackMidiDriver::Attach()
         }
         port = fGraphManager->GetPort(port_index);
         port->SetAlias(alias);
+        port->SetLatencyRange(JackCaptureLatency, &latency_range);
         fCapturePortList[i] = port_index;
         jack_log("JackMidiDriver::Attach fCapturePortList[i] port_index = %ld", port_index);
     }
 
+    if (!fEngineControl->fSyncMode) {
+        latency += fEngineControl->fBufferSize;;
+        latency_range.max = latency_range.min = latency;
+    }
+
     for (i = 0; i < fPlaybackChannels; i++) {
         snprintf(alias, sizeof(alias) - 1, "%s:%s:in%d", fAliasName, fPlaybackDriverName, i + 1);
         snprintf(name, sizeof(name) - 1, "%s:playback_%d", fClientControl.fName, i + 1);
@@ -100,6 +109,7 @@ int JackMidiDriver::Attach()
         }
         port = fGraphManager->GetPort(port_index);
         port->SetAlias(alias);
+        port->SetLatencyRange(JackPlaybackLatency, &latency_range);
         fPlaybackPortList[i] = port_index;
         jack_log("JackMidiDriver::Attach fPlaybackPortList[i] port_index = %ld", port_index);
     }
diff --git a/macosx/coremidi/JackCoreMidiDriver.cpp b/macosx/coremidi/JackCoreMidiDriver.cpp
index 1cb7176b..233ac8dd 100644
--- a/macosx/coremidi/JackCoreMidiDriver.cpp
+++ b/macosx/coremidi/JackCoreMidiDriver.cpp
@@ -227,9 +227,12 @@ int JackCoreMidiDriver::Attach()
     char name[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
     char endpoint_name[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
     char alias[JACK_CLIENT_NAME_SIZE + JACK_PORT_NAME_SIZE];
+    jack_latency_range_t latency_range;
+    jack_nframes_t latency = fEngineControl->fBufferSize;
     int i;
 
     jack_log("JackCoreMidiDriver::Attach fBufferSize = %ld fSampleRate = %ld", fEngineControl->fBufferSize, fEngineControl->fSampleRate);
+    latency_range.max = latency_range.min = latency;
 
     for (i = 0; i < fCaptureChannels; i++) {
 
@@ -249,10 +252,16 @@ int JackCoreMidiDriver::Attach()
         }
         port = fGraphManager->GetPort(port_index);
         port->SetAlias(alias);
+        port->SetLatencyRange(JackCaptureLatency, &latency_range);
         fCapturePortList[i] = port_index;
         jack_log("JackCoreMidiDriver::Attach fCapturePortList[i] port_index = %ld", port_index);
     }
 
+    if (!fEngineControl->fSyncMode) {
+        latency += fEngineControl->fBufferSize;;
+        latency_range.max = latency_range.min = latency;
+    }
+
     for (i = 0; i < fPlaybackChannels; i++) {
 
         err = MIDIObjectGetStringProperty(fMidiSource[i], kMIDIPropertyName, &pname);
@@ -271,6 +280,7 @@ int JackCoreMidiDriver::Attach()
         }
         port = fGraphManager->GetPort(port_index);
         port->SetAlias(alias);
+        port->SetLatencyRange(JackPlaybackLatency, &latency_range);
         fPlaybackPortList[i] = port_index;
         jack_log("JackCoreMidiDriver::Attach fPlaybackPortList[i] port_index = %ld", port_index);
     }