diff --git a/SyllableDetector.xcodeproj/project.pbxproj b/SyllableDetector.xcodeproj/project.pbxproj
index 8501b91..76cde2d 100644
--- a/SyllableDetector.xcodeproj/project.pbxproj
+++ b/SyllableDetector.xcodeproj/project.pbxproj
@@ -326,6 +326,7 @@
 					};
 					D8E2DB501D00C74500FC6AE2 = {
 						CreatedOnToolsVersion = 7.3.1;
+						LastSwiftMigration = 0800;
 					};
 				};
 			};
@@ -574,6 +575,7 @@
 				CLANG_ANALYZER_NONNULL = YES;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = "Common/Common-Bridging-Header.h";
+				SWIFT_VERSION = 3.0;
 			};
 			name = Debug;
 		};
@@ -584,6 +586,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = "Common/Common-Bridging-Header.h";
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
+				SWIFT_VERSION = 3.0;
 			};
 			name = Release;
 		};
diff --git a/SyllableDetectorCLI/OutputStream.swift b/SyllableDetectorCLI/OutputStream.swift
index a20b158..2f7d912 100644
--- a/SyllableDetectorCLI/OutputStream.swift
+++ b/SyllableDetectorCLI/OutputStream.swift
@@ -8,22 +8,14 @@
 
 import Foundation
 
-extension OutputStreamType {
+extension TextOutputStream {
     mutating func writeLine(string: String) {
         self.write("\(string)\n")
     }
 }
 
-class StandardOutputStream: OutputStreamType {
-    func write(string: String) {
-        let stdout = NSFileHandle.fileHandleWithStandardOutput()
-        stdout.writeData(string.dataUsingEncoding(NSUTF8StringEncoding)!)
-    }
-}
-
-class StandardErrorOutputStream: OutputStreamType {
-    func write(string: String) {
-        let stderr = NSFileHandle.fileHandleWithStandardError()
-        stderr.writeData(string.dataUsingEncoding(NSUTF8StringEncoding)!)
+extension FileHandle {
+    func writeLine(_ string: String) {
+        write("\(string)\n".data(using: String.Encoding.utf8)!)
     }
 }
diff --git a/SyllableDetectorCLI/TrackDetector.swift b/SyllableDetectorCLI/TrackDetector.swift
index 73f485a..dbca549 100644
--- a/SyllableDetectorCLI/TrackDetector.swift
+++ b/SyllableDetectorCLI/TrackDetector.swift
@@ -69,7 +69,7 @@ class TrackDetector
             
             // look for detection
             var hasDetection = false
-            for (i, d) in detector.lastOutputs.enumerate() {
+            for (i, d) in detector.lastOutputs.enumerated() {
                 if Double(d) >= detector.config.thresholds[i] {
                     hasDetection = true
                     break
diff --git a/SyllableDetectorCLI/main.swift b/SyllableDetectorCLI/main.swift
index adf2da9..76002bf 100644
--- a/SyllableDetectorCLI/main.swift
+++ b/SyllableDetectorCLI/main.swift
@@ -11,7 +11,7 @@ import AVFoundation
 
 // UTILITY
 
-private var stderr = StandardErrorOutputStream()
+private var stderr = FileHandle.standardError
 
 // PARSE COMMAND LINE
 
@@ -60,7 +60,7 @@ do {
     config = try SyllableDetectorConfig(fromTextFile: networkPath.value!)
 }
 catch {
-    print("Unable to load the network configuration: \(error)", toStream: &stderr)
+    stderr.writeLine("Unable to load the network configuration: \(error)")
     fatalError()
 }
 
@@ -71,39 +71,39 @@ audioPaths.value!.forEach {
     
     // 2b. open asset
     
-    let assetRead = AVAsset(URL: NSURL(fileURLWithPath: audioPath))
+    let assetRead = AVAsset(url: URL(fileURLWithPath: audioPath))
     let avReader: AVAssetReader
     do {
         avReader = try AVAssetReader(asset: assetRead)
     }
     catch {
-        print("Unable to read \(audioPath): \(error)", toStream: &stderr)
+        stderr.writeLine("Unable to read \(audioPath): \(error)")
         return
     }
     
     // get  number of audio tracks
-    let tracksAudio = assetRead.tracksWithMediaType(AVMediaTypeAudio)
+    let tracksAudio = assetRead.tracks(withMediaType: AVMediaTypeAudio)
     guard 0 < tracksAudio.count else {
-        print("No audio tracks found in \(audioPath).", toStream: &stderr)
+        stderr.writeLine("No audio tracks found in \(audioPath).")
         return
     }
     
     // make detectors
-    let potentialTrackDetectors = tracksAudio.enumerate().map {
+    let potentialTrackDetectors = tracksAudio.enumerated().map {
         (i, track) in
         return TrackDetector(track: track, config: config, channel: i)
     }
     
     // validate
     let trackDetectors = potentialTrackDetectors.filter {
-        return avReader.canAddOutput($0.reader)
+        return avReader.canAdd($0.reader)
     }
     if trackDetectors.count == 0 {
-        print("Can not read audio tracks found in \(audioPath).", toStream: &stderr)
+        stderr.writeLine("Can not read audio tracks found in \(audioPath).")
         return
     }
     if trackDetectors.count < potentialTrackDetectors.count {
-        print("Can not read from \(potentialTrackDetectors.count - trackDetectors.count) audio track(s) in \(audioPath). Skipping those tracks.", toStream: &stderr)
+        stderr.writeLine("Can not read from \(potentialTrackDetectors.count - trackDetectors.count) audio track(s) in \(audioPath). Skipping those tracks.")
     }
     
     // add all
@@ -114,12 +114,12 @@ audioPaths.value!.forEach {
         }
         
         // add it
-        avReader.addOutput($0.reader)
+        avReader.add($0.reader)
     }
     
     // start reading
     if !avReader.startReading() {
-        print("Can not start reading \(audioPath): \(avReader.error).", toStream: &stderr)
+        stderr.writeLine("Can not start reading \(audioPath): \(avReader.error).")
         return
     }
     
@@ -129,7 +129,7 @@ audioPaths.value!.forEach {
         print("\(audioPath)")
     }
     
-    while avReader.status == AVAssetReaderStatus.Reading {
+    while avReader.status == AVAssetReaderStatus.reading {
         for trackDetector in trackDetectors {
             trackDetector.process()
         }