diff --git a/MetaballsKit/Memory.swift b/MetaballsKit/Memory.swift
index c404213..22b0cca 100644
--- a/MetaballsKit/Memory.swift
+++ b/MetaballsKit/Memory.swift
@@ -11,7 +11,7 @@ import Foundation
 extension UnsafeMutableRawPointer {
     func writeAndAdvance<T>(value: inout T) -> UnsafeMutableRawPointer {
         let stride = MemoryLayout.stride(ofValue: value)
-        copyBytes(from: &value, count: stride)
+        copyMemory(from: &value, byteCount: stride)
         return advanced(by: stride)
     }
 }
diff --git a/MetaballsKit/Metaballs.swift b/MetaballsKit/Metaballs.swift
index dae6d0f..058ee96 100644
--- a/MetaballsKit/Metaballs.swift
+++ b/MetaballsKit/Metaballs.swift
@@ -63,7 +63,7 @@ public struct Parameters {
     public mutating func write(to buffer: MTLBuffer, offset: Int = 0) {
         let start = buffer.contents().advanced(by: offset)
         let stride = MemoryLayout.stride(ofValue: self)
-        start.copyBytes(from: &self, count: stride)
+        start.copyMemory(from: &self, byteCount: stride)
     }
 }
 
@@ -226,7 +226,9 @@ public class Field {
             var ptr = ballBuffer.contents()
             var idx = 0
             for var ball in self.balls {
-                ballBuffer.addDebugMarker("Ball \(idx)", range: NSRange(location: ballBuffer.contents().distance(to: ptr), length: 16))
+                if let range = Range(NSRange(location: ballBuffer.contents().distance(to: ptr), length: 16)) {
+                    ballBuffer.addDebugMarker("Ball \(idx)", range: range)
+                }
                 ptr = write(value: &ball.position.x, to: ptr)
                 ptr = write(value: &ball.position.y, to: ptr)
                 var r = ball.radius
@@ -242,7 +244,7 @@ public class Field {
 
     private func write<T>(value: inout T, to ptr: UnsafeMutableRawPointer) -> UnsafeMutableRawPointer {
         let sizeOfType = MemoryLayout<T>.stride
-        ptr.copyBytes(from: &value, count: sizeOfType)
+        ptr.copyMemory(from: &value, byteCount: sizeOfType)
         return ptr.advanced(by: sizeOfType)
     }
 
diff --git a/MetaballsKit/Renderer.swift b/MetaballsKit/Renderer.swift
index f45ba24..8129dc6 100644
--- a/MetaballsKit/Renderer.swift
+++ b/MetaballsKit/Renderer.swift
@@ -73,9 +73,12 @@ public class Renderer: NSObject, MTKViewDelegate {
         guard let device = MTLCreateSystemDefaultDevice() else {
             fatalError("Unable to create Metal system device")
         }
+        guard let queue = device.makeCommandQueue() else {
+            fatalError("Unable to create Metal command queue")
+        }
 
         self.device = device
-        commandQueue = device.makeCommandQueue()
+        commandQueue = queue
 
         super.init()
     }
@@ -109,24 +112,24 @@ public class Renderer: NSObject, MTKViewDelegate {
 
         field.update()
 
-        let buffer = commandQueue.makeCommandBuffer()
-        buffer.label = "Render"
+        if let buffer = commandQueue.makeCommandBuffer() {
+            buffer.label = "Render"
 
-        if let renderPass = view.currentRenderPassDescriptor, let renderPipelineState = renderPipelineState {
-            let encoder = buffer.makeRenderCommandEncoder(descriptor: renderPass)
-            encoder.label = "Render Pass"
-            encoder.setViewport(MTLViewport(originX: 0.0, originY: 0.0, width: Double(view.drawableSize.width), height: Double(view.drawableSize.height), znear: -1.0, zfar: 1.0))
-            encoder.setRenderPipelineState(renderPipelineState)
-            encoder.setVertexBytes(points, length: points.count * MemoryLayout<Vertex>.stride, index: 0)
-            encoder.setFragmentBuffer(field.parametersBuffer, offset: 0, index: 0)
-            encoder.setFragmentBuffer(field.ballBuffer, offset: 0, index: 1)
-            encoder.drawPrimitives(type: .triangle, vertexStart: 0, vertexCount: 6)
-            encoder.endEncoding()
+            if let renderPass = view.currentRenderPassDescriptor, let renderPipelineState = renderPipelineState, let encoder = buffer.makeRenderCommandEncoder(descriptor: renderPass) {
+                encoder.label = "Render Pass"
+                encoder.setViewport(MTLViewport(originX: 0.0, originY: 0.0, width: Double(view.drawableSize.width), height: Double(view.drawableSize.height), znear: -1.0, zfar: 1.0))
+                encoder.setRenderPipelineState(renderPipelineState)
+                encoder.setVertexBytes(points, length: points.count * MemoryLayout<Vertex>.stride, index: 0)
+                encoder.setFragmentBuffer(field.parametersBuffer, offset: 0, index: 0)
+                encoder.setFragmentBuffer(field.ballBuffer, offset: 0, index: 1)
+                encoder.drawPrimitives(type: .triangle, vertexStart: 0, vertexCount: 6)
+                encoder.endEncoding()
 
-            if let drawable = view.currentDrawable {
-                buffer.present(drawable)
+                if let drawable = view.currentDrawable {
+                    buffer.present(drawable)
+                }
             }
+            buffer.commit()
         }
-        buffer.commit()
     }
 }