diff --git a/JoyKit/JOYController.m b/JoyKit/JOYController.m
index b4810ab..f9f0775 100644
--- a/JoyKit/JOYController.m
+++ b/JoyKit/JOYController.m
@@ -5,6 +5,8 @@
 #import "JOYEmulatedButton.h"
 #include <IOKit/hid/IOHIDLib.h>
 
+#define PWM_RESOLUTION 16
+
 static NSString const *JOYAxisGroups = @"JOYAxisGroups";
 static NSString const *JOYReportIDFilters = @"JOYReportIDFilters";
 static NSString const *JOYButtonUsageMapping = @"JOYButtonUsageMapping";
@@ -130,7 +132,7 @@ typedef struct __attribute__((packed)) {
     
     _physicallyConnected = true;
     _logicallyConnected = true;
-    _device = device;
+    _device = (IOHIDDeviceRef)CFRetain(device);
     _serialSuffix = suffix;
 
     IOHIDDeviceRegisterInputValueCallback(device, HIDInput, (void *)self);
@@ -603,11 +605,17 @@ typedef struct __attribute__((packed)) {
 
 - (void)pwmThread
 {
-    while (_rumblePWMRatio != 0) {
-        [_rumbleElement setValue:1];
-        [NSThread sleepForTimeInterval:_rumblePWMRatio / 10];
-        [_rumbleElement setValue:0];
-        [NSThread sleepForTimeInterval:(1 - _rumblePWMRatio) / 10];
+    /* TODO: This does not handle correctly the case of having a multi-port controller where more than one controller
+             uses rumble. */
+    unsigned rumbleCounter = 0;
+    while (self.connected) {
+        if ([_rumbleElement setValue:rumbleCounter < round(_rumblePWMRatio * PWM_RESOLUTION)]) {
+            break;
+        }
+        rumbleCounter += round(_rumblePWMRatio * PWM_RESOLUTION);
+        if (rumbleCounter >= PWM_RESOLUTION) {
+            rumbleCounter -= PWM_RESOLUTION;
+        }
     }
     [_rumblePWMThreadLock lock];
     _rumblePWMThreadRunning = false;
@@ -659,6 +667,7 @@ typedef struct __attribute__((packed)) {
     else {
         if (_rumbleElement.max == 1 && _rumbleElement.min == 0) {
             [_rumblePWMThreadLock lock];
+            _rumblePWMRatio = amp;
             if (!_rumblePWMThreadRunning) { // PWM thread not running, start it.
                 if (amp != 0) {
                     _rumblePWMRatio = amp;
@@ -666,14 +675,6 @@ typedef struct __attribute__((packed)) {
                     [self performSelectorInBackground:@selector(pwmThread) withObject:nil];
                 }
             }
-            else {
-                if (amp == 0) { // Thread is running, signal it to stop
-                    _rumblePWMRatio = 0;
-                }
-                else {
-                    _rumblePWMRatio = amp;
-                }
-            }
             [_rumblePWMThreadLock unlock];
         }
         else {
@@ -771,4 +772,12 @@ typedef struct __attribute__((packed)) {
     IOHIDManagerRegisterDeviceRemovalCallback(manager, HIDDeviceRemoved, NULL);
     IOHIDManagerScheduleWithRunLoop(manager, [runloop getCFRunLoop], kCFRunLoopDefaultMode);
 }
+
+- (void)dealloc
+{
+    if (_device) {
+        CFRelease(_device);
+        _device = NULL;
+    }
+}
 @end
diff --git a/JoyKit/JOYElement.h b/JoyKit/JOYElement.h
index 860c247..0e917dd 100644
--- a/JoyKit/JOYElement.h
+++ b/JoyKit/JOYElement.h
@@ -5,8 +5,8 @@
 - (instancetype)initWithElement:(IOHIDElementRef)element;
 - (int32_t)value;
 - (NSData *)dataValue;
-- (void)setValue:(uint32_t)value;
-- (void)setDataValue:(NSData *)value;
+- (IOReturn)setValue:(uint32_t)value;
+- (IOReturn)setDataValue:(NSData *)value;
 @property (readonly) uint16_t usage;
 @property (readonly) uint16_t usagePage;
 @property (readonly) uint32_t uniqueID;
diff --git a/JoyKit/JOYElement.m b/JoyKit/JOYElement.m
index 6539c2e..4050312 100644
--- a/JoyKit/JOYElement.m
+++ b/JoyKit/JOYElement.m
@@ -81,18 +81,20 @@
     return [NSData dataWithBytes:IOHIDValueGetBytePtr(value) length:IOHIDValueGetLength(value)];
 }
 
-- (void)setValue:(uint32_t)value
+- (IOReturn)setValue:(uint32_t)value
 {
     IOHIDValueRef ivalue = IOHIDValueCreateWithIntegerValue(NULL, (__bridge IOHIDElementRef)_element, 0, value);
-    IOHIDDeviceSetValue(_device, (__bridge IOHIDElementRef)_element, ivalue);
+    IOReturn ret = IOHIDDeviceSetValue(_device, (__bridge IOHIDElementRef)_element, ivalue);
     CFRelease(ivalue);
+    return ret;
 }
 
-- (void)setDataValue:(NSData *)value
+- (IOReturn)setDataValue:(NSData *)value
 {
     IOHIDValueRef ivalue = IOHIDValueCreateWithBytes(NULL, (__bridge IOHIDElementRef)_element, 0, value.bytes, value.length);
-    IOHIDDeviceSetValue(_device, (__bridge IOHIDElementRef)_element, ivalue);
+    IOReturn ret = IOHIDDeviceSetValue(_device, (__bridge IOHIDElementRef)_element, ivalue);
     CFRelease(ivalue);
+    return ret;
 }
 
 /* For use as a dictionary key */
diff --git a/JoyKit/JOYSubElement.m b/JoyKit/JOYSubElement.m
index 55e289e..c94badc 100644
--- a/JoyKit/JOYSubElement.m
+++ b/JoyKit/JOYSubElement.m
@@ -65,15 +65,15 @@
     return ret;
 }
 
-- (void)setValue: (uint32_t) value
+- (IOReturn)setValue: (uint32_t) value
 {
     NSMutableData *dataValue = [[_parent dataValue] mutableCopy];
-    if (!dataValue) return;
-    if (_size > 32) return;
-    if (_size + (_offset % 8) > 32) return;
+    if (!dataValue) return -1;
+    if (_size > 32) return -1;
+    if (_size + (_offset % 8) > 32) return -1;
     size_t parentLength = dataValue.length;
-    if (_size > parentLength * 8) return;
-    if (_size + _offset >= parentLength * 8) return;
+    if (_size > parentLength * 8) return -1;
+    if (_size + _offset >= parentLength * 8) return -1;
     uint8_t *bytes = dataValue.mutableBytes;
     
     uint8_t temp[4] = {0,};
@@ -81,7 +81,7 @@
     (*(uint32_t *)temp) &= ~((1 << (_size - 1)) << (_offset % 8));
     (*(uint32_t *)temp) |= (value) << (_offset % 8);
     memcpy(bytes + _offset / 8, temp, (_offset + _size - 1) / 8 - _offset / 8 + 1);
-    [_parent setDataValue:dataValue];
+    return [_parent setDataValue:dataValue];
 }
 
 - (NSData *)dataValue
@@ -90,9 +90,10 @@
     return nil;
 }
 
-- (void)setDataValue:(NSData *)data
+- (IOReturn)setDataValue:(NSData *)data
 {
     [self doesNotRecognizeSelector:_cmd];
+    return -1;
 }