diff --git a/src/swift/Data.swift b/src/swift/Data.swift
index 7acf50d65..6437ea48c 100644
--- a/src/swift/Data.swift
+++ b/src/swift/Data.swift
@@ -65,7 +65,11 @@ public struct DispatchData : RandomAccessCollection {
 	}
 
 	internal init(data: dispatch_data_t) {
-		__wrapped = __DispatchData(data: data)
+		__wrapped = __DispatchData(data: data, owned: true)
+	}
+
+	internal init(borrowedData: dispatch_data_t) {
+		__wrapped = __DispatchData(data: borrowedData, owned: false)
 	}
 
 	public var count: Int {
@@ -110,7 +114,7 @@ public struct DispatchData : RandomAccessCollection {
 	/// - parameter data: The data to append to this data.
 	public mutating func append(_ other: DispatchData) {
 		let data = CDispatch.dispatch_data_create_concat(__wrapped.__wrapped, other.__wrapped.__wrapped)
-		__wrapped = __DispatchData(data: data)
+		__wrapped = __DispatchData(data: data, owned: true)
 	}
 
 	/// Append a buffer of bytes to the data.
@@ -244,7 +248,7 @@ public struct DispatchDataIterator : IteratorProtocol, Sequence {
 	public init(_data: DispatchData) {
 		var ptr: UnsafeRawPointer?
 		self._count = 0
-		self._data = __DispatchData(data: CDispatch.dispatch_data_create_map(_data.__wrapped.__wrapped, &ptr, &self._count))
+		self._data = __DispatchData(data: CDispatch.dispatch_data_create_map(_data.__wrapped.__wrapped, &ptr, &self._count), owned: true)
 		self._ptr = ptr
 		self._position = _data.startIndex
 
diff --git a/src/swift/IO.swift b/src/swift/IO.swift
index 10c719919..8ce417aa7 100644
--- a/src/swift/IO.swift
+++ b/src/swift/IO.swift
@@ -36,13 +36,13 @@ public extension DispatchIO {
 
 	public class func read(fromFileDescriptor: Int32, maxLength: Int, runningHandlerOn queue: DispatchQueue, handler: @escaping (_ data: DispatchData, _ error: Int32) -> Void) {
 		dispatch_read(fromFileDescriptor, maxLength, queue.__wrapped) { (data: dispatch_data_t, error: Int32) in
-			handler(DispatchData(data: data), error)
+			handler(DispatchData(borrowedData: data), error)
 		}
 	}
 
 	public class func write(toFileDescriptor: Int32, data: DispatchData, runningHandlerOn queue: DispatchQueue, handler: @escaping (_ data: DispatchData?, _ error: Int32) -> Void) {
 		dispatch_write(toFileDescriptor, data.__wrapped.__wrapped, queue.__wrapped) { (data: dispatch_data_t?, error: Int32) in
-			handler(data.flatMap { DispatchData(data: $0) }, error)
+			handler(data.flatMap { DispatchData(borrowedData: $0) }, error)
 		}
 	}
 
@@ -77,13 +77,13 @@ public extension DispatchIO {
 
 	public func read(offset: off_t, length: Int, queue: DispatchQueue, ioHandler: @escaping (_ done: Bool, _ data: DispatchData?, _ error: Int32) -> Void) {
 		dispatch_io_read(self.__wrapped, offset, length, queue.__wrapped) { (done: Bool, data: dispatch_data_t?, error: Int32) in
-			ioHandler(done, data.flatMap { DispatchData(data: $0) }, error)
+			ioHandler(done, data.flatMap { DispatchData(borrowedData: $0) }, error)
 		}
 	}
 
 	public func write(offset: off_t, data: DispatchData, queue: DispatchQueue, ioHandler: @escaping (_ done: Bool, _ data: DispatchData?, _ error: Int32) -> Void) {
 		dispatch_io_write(self.__wrapped, offset, data.__wrapped.__wrapped, queue.__wrapped) { (done: Bool, data: dispatch_data_t?, error: Int32) in
-			ioHandler(done, data.flatMap { DispatchData(data: $0) }, error)
+			ioHandler(done, data.flatMap { DispatchData(borrowedData: $0) }, error)
 		}
 	}
 
diff --git a/src/swift/Wrapper.swift b/src/swift/Wrapper.swift
index ea340e20c..9c96c0eed 100644
--- a/src/swift/Wrapper.swift
+++ b/src/swift/Wrapper.swift
@@ -192,17 +192,21 @@ extension DispatchSource : DispatchSourceProcess,
 
 internal class __DispatchData : DispatchObject {
 	internal let __wrapped:dispatch_data_t
+	internal let __owned:Bool
 
 	final internal override func wrapped() -> dispatch_object_t {
 		return unsafeBitCast(__wrapped, to: dispatch_object_t.self)
 	}
 
-	internal init(data:dispatch_data_t) {
+	internal init(data:dispatch_data_t, owned:Bool) {
 		__wrapped = data
+		__owned = owned
 	}
 
 	deinit {
-		_swift_dispatch_release(wrapped())
+		if __owned {
+			_swift_dispatch_release(wrapped())
+		}
 	}
 }