diff --git a/MasKit/ExternalCommands/ExternalCommand.swift b/MasKit/ExternalCommands/ExternalCommand.swift
index 4ffb767..df50e13 100644
--- a/MasKit/ExternalCommands/ExternalCommand.swift
+++ b/MasKit/ExternalCommands/ExternalCommand.swift
@@ -13,8 +13,8 @@ public protocol ExternalCommand {
 
     var process: Process { get }
 
-    var stdout: String? { get }
-    var stderr: String? { get }
+    var stdout: String { get }
+    var stderr: String { get }
     var stdoutPipe: Pipe { get }
     var stderrPipe: Pipe { get }
 
@@ -23,19 +23,19 @@ public protocol ExternalCommand {
     var failed: Bool { get }
 
     /// Runs the command.
-    mutating func run() throws
+    func run() throws
 }
 
 /// Common implementation
 extension ExternalCommand {
-    public var stdout: String? { get {
+    public var stdout: String { get {
         let data = stdoutPipe.fileHandleForReading.readDataToEndOfFile()
-        return String(data: data, encoding: .utf8)
+        return String(data: data, encoding: .utf8) ?? ""
     }}
 
-    public var stderr: String? { get {
+    public var stderr: String { get {
         let data = stderrPipe.fileHandleForReading.readDataToEndOfFile()
-        return String(data: data, encoding: .utf8)
+        return String(data: data, encoding: .utf8) ?? ""
     }}
 
     public var exitCode: Int? { get {
@@ -51,7 +51,7 @@ extension ExternalCommand {
     }}
 
     /// Runs the command.
-    public mutating func run() throws {
+    public func run() throws {
         process.standardOutput = stdoutPipe
         process.standardError = stderrPipe
         process.arguments = arguments
diff --git a/MasKit/ExternalCommands/TrashCommand.swift b/MasKit/ExternalCommands/TrashCommand.swift
index 2e0c74d..ddad5eb 100644
--- a/MasKit/ExternalCommands/TrashCommand.swift
+++ b/MasKit/ExternalCommands/TrashCommand.swift
@@ -6,7 +6,9 @@
 //  Copyright © 2019 mas-cli. All rights reserved.
 //
 
-/// CLI command
+/// Wrapper for the external trash command. Relies on the "trash" command
+/// from Homebrew. Trash requires el_capitan or higher for core bottles:
+/// https://github.com/Homebrew/homebrew-core/blob/master/Formula/trash.rb
 public struct TrashCommand: ExternalCommand {
     public var binaryPath: String
     public var arguments: [String]
diff --git a/MasKit/MasAppLibrary.swift b/MasKit/MasAppLibrary.swift
index b03066b..dfaf02f 100644
--- a/MasKit/MasAppLibrary.swift
+++ b/MasKit/MasAppLibrary.swift
@@ -22,8 +22,9 @@ public class MasAppLibrary: AppLibrary {
         return products
     }()
 
-    private let trashCommand: ExternalCommand
+    private var trashCommand: ExternalCommand
 
+    /// Designated initializer
     public init(trashCommand: ExternalCommand = TrashCommand()) {
         self.trashCommand = trashCommand
     }
@@ -41,50 +42,17 @@ public class MasAppLibrary: AppLibrary {
     /// - Parameter app: App to be removed.
     /// - Throws: Error if there is a problem.
     public func uninstallApp(app: SoftwareProduct) throws {
-        let status = trash(path: app.bundlePath)
-        if !status {
+        trashCommand.arguments = [app.bundlePath]
+        do {
+            try trashCommand.run()
+        } catch {
+            printError("Unable to launch trash command")
+            throw MASError.uninstallFailed
+        }
+        if trashCommand.failed {
+            let reason = trashCommand.process.terminationReason
+            printError("Uninstall failed: (\(reason)) \(trashCommand.stderr)")
             throw MASError.uninstallFailed
         }
     }
-
-    /// Runs the trash command in another process. Relies on the "trash" command
-    /// from Homebrew. Trash requires el_capitan or higher for core bottles:
-    /// https://github.com/Homebrew/homebrew-core/blob/master/Formula/trash.rb
-    ///
-    /// - Parameter path: Absolute path to the application bundle to uninstall.
-    /// - Returns: true on success; fail on error
-    func trash(path: String) -> Bool {
-        let binaryPath = "/usr/local/bin/trash"
-        let process = Process()
-        let stdout = Pipe()
-        let stderr = Pipe()
-
-        process.standardOutput = stdout
-        process.standardError = stderr
-        process.arguments = [path]
-
-        if #available(OSX 10.13, *) {
-            process.executableURL = URL(fileURLWithPath: binaryPath)
-            do {
-                try process.run()
-            } catch {
-                printError("Unable to launch trash command")
-                return false
-            }
-        } else {
-            process.launchPath = binaryPath
-            process.launch()
-        }
-
-        process.waitUntilExit()
-
-        if process.terminationStatus == 0 {
-            return true
-        } else {
-            let reason = process.terminationReason
-            let output = stderr.fileHandleForReading.readDataToEndOfFile()
-            printError("Uninstall failed: \(reason)\n\(String(data: output, encoding: .utf8)!)")
-            return false
-        }
-    }
 }