--- a/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_MidiIn.cpp	Mon Apr 23 12:01:46 2018 -0400
+++ b/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_MidiIn.cpp	Mon Apr 23 16:15:26 2018 -0700
@@ -252,7 +252,7 @@
 }
 
 INT32 getMidiInCaps(INT32 deviceID, MIDIINCAPSW* caps, INT32* err) {
-    (*err) = midiInGetDevCapsW(deviceID, caps, sizeof(MIDIINCAPS));
+    (*err) = midiInGetDevCapsW(deviceID, caps, sizeof(MIDIINCAPSW));
     return ((*err) == MMSYSERR_NOERROR);
 }
 
@@ -260,6 +260,7 @@
     MIDIINCAPSW midiInCaps;
     INT32 err;
 
+    memset(&midiInCaps, 0, sizeof(midiInCaps));
     if (getMidiInCaps(deviceID, &midiInCaps, &err)) {
         UnicodeToUTF8AndCopy(name, midiInCaps.szPname, nameLength);
         return MIDI_SUCCESS;
@@ -284,6 +285,7 @@
     MIDIINCAPSW midiInCaps;
     INT32 err = MIDI_NOT_SUPPORTED;
 
+    memset(&midiInCaps, 0, sizeof(midiInCaps));
     if (getMidiInCaps(deviceID, &midiInCaps, &err) && (nameLength>7)) {
         sprintf(name, "%d.%d", (midiInCaps.vDriverVersion & 0xFF00) >> 8, midiInCaps.vDriverVersion & 0xFF);
         return MIDI_SUCCESS;

--- a/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_MidiOut.c	Mon Apr 23 12:01:46 2018 -0400
+++ b/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_MidiOut.c	Mon Apr 23 16:15:26 2018 -0700
@@ -70,12 +70,13 @@
 
 
 INT32 getMidiOutCaps(INT32 deviceID, MIDIOUTCAPSW* caps, INT32* err) {
+    UINT_PTR id;
     if (deviceID == 0) {
-        deviceID = MIDI_MAPPER;
+        id = MIDI_MAPPER;
     } else {
-        deviceID--;
+        id = (UINT_PTR)(deviceID-1);
     }
-    (*err) = (INT32) midiOutGetDevCapsW(deviceID, caps, sizeof(MIDIOUTCAPS));
+    (*err) = (INT32) midiOutGetDevCapsW(id, caps, sizeof(MIDIOUTCAPSW));
     return ((*err) == MMSYSERR_NOERROR);
 }
 
@@ -84,6 +85,7 @@
     MIDIOUTCAPSW midiOutCaps;
     INT32 err;
 
+    memset(&midiOutCaps, 0, sizeof(midiOutCaps));
     if (getMidiOutCaps(deviceID, &midiOutCaps, &err)) {
         UnicodeToUTF8AndCopy(name, midiOutCaps.szPname, nameLength);
         return MIDI_SUCCESS;
@@ -103,6 +105,7 @@
     char *desc;
     INT32 err;
 
+    memset(&midiOutCaps, 0, sizeof(midiOutCaps));
     if (getMidiOutCaps(deviceID, &midiOutCaps, &err)) {
         int tech = (int)midiOutCaps.wTechnology;
         switch(tech) {
@@ -139,6 +142,7 @@
     MIDIOUTCAPSW midiOutCaps;
     INT32 err;
 
+    memset(&midiOutCaps, 0, sizeof(midiOutCaps));
     if (getMidiOutCaps(deviceID, &midiOutCaps, &err) && nameLength>7) {
         sprintf(name, "%d.%d", (midiOutCaps.vDriverVersion & 0xFF00) >> 8, midiOutCaps.vDriverVersion & 0xFF);
         return MIDI_SUCCESS;

--- a/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_Ports.c	Mon Apr 23 12:01:46 2018 -0400
+++ b/src/java.desktop/windows/native/libjsound/PLATFORM_API_WinOS_Ports.c	Mon Apr 23 16:15:26 2018 -0700
@@ -357,7 +357,7 @@
 
 INT32 PORT_GetPortMixerDescription(INT32 mixerIndex, PortMixerDescription* description) {
     MIXERCAPSW mixerCaps;
-    if (mixerGetDevCapsW(mixerIndex, &mixerCaps, sizeof(MIXERCAPS)) == MMSYSERR_NOERROR) {
+    if (mixerGetDevCapsW(mixerIndex, &mixerCaps, sizeof(MIXERCAPSW)) == MMSYSERR_NOERROR) {
         UnicodeToUTF8AndCopy(description->name, mixerCaps.szPname, PORT_STRING_LENGTH);
         sprintf(description->version, "%d.%d", (mixerCaps.vDriverVersion & 0xFF00) >> 8, mixerCaps.vDriverVersion & 0xFF);
         strncpy(description->description, "Port Mixer", PORT_STRING_LENGTH-1);
@@ -368,9 +368,9 @@
 
 int getDestinationCount(HMIXER handle) {
     int ret = 0;
-    MIXERCAPS mixerCaps;
+    MIXERCAPSW mixerCaps;
 
-    if (mixerGetDevCaps((UINT_PTR) handle, &mixerCaps, sizeof(MIXERCAPS)) == MMSYSERR_NOERROR) {
+    if (mixerGetDevCapsW((UINT_PTR) handle, &mixerCaps, sizeof(MIXERCAPSW)) == MMSYSERR_NOERROR) {
         ret = mixerCaps.cDestinations;
     }
     return ret;