diff --git a/metaltest.swift b/metaltest.swift
index 8256f8a..e13e53a 100644
--- a/metaltest.swift
+++ b/metaltest.swift
@@ -1,11 +1,11 @@
 import Metal
 
-var supportedDevices: [MTLDevice] = MTLCopyAllDevices()
+let supportedDevices: [MTLDevice] = MTLCopyAllDevices()
 
 if (supportedDevices.count > 0)
 {
     for device in supportedDevices {
-        var isSupported = device.supportsFeatureSet(MTLFeatureSet.osx_GPUFamily1_v1)
+        let isSupported = device.supportsFeatureSet(MTLFeatureSet.osx_GPUFamily1_v1)
         print("\(device.name), supported: \(isSupported)")
     }
 }