diff --git a/Sources/SwiftShell/Stream/Stream.swift b/Sources/SwiftShell/Stream/Stream.swift
index 52dd42b..1a315b3 100644
--- a/Sources/SwiftShell/Stream/Stream.swift
+++ b/Sources/SwiftShell/Stream/Stream.swift
@@ -119,8 +119,11 @@ extension ReadableStream {
 		/// - Note: if the stream is read from outside of the handler, or more than once inside
 		/// the handler, it may be called once when stream is closed and empty.
 		public func onOutput(_ handler: @escaping (ReadableStream) -> Void) {
-			filehandle.readabilityHandler = { [unowned self] _ in
-				handler(self)
+			filehandle.readabilityHandler = { [weak self] _ in
+                guard let wSelf = self else {
+                    return
+                }
+				handler(wSelf)
 			}
 		}
 
diff --git a/SwiftShell.podspec b/SwiftShell.podspec
index 7258637..7f5ad31 100644
--- a/SwiftShell.podspec
+++ b/SwiftShell.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = 'SwiftShell'
-  s.version      = '4.0.0'
+  s.version      = '4.0.1'
   s.summary      = 'A Swift framework for shell scripting.'
   s.description  = 'SwiftShell is a library for creating command-line applications and running shell commands in Swift.'
   s.homepage     = 'https://github.com/kareman/SwiftShell'