Index: src/OFTLSSocket.h
==================================================================
--- src/OFTLSSocket.h
+++ src/OFTLSSocket.h
@@ -64,10 +64,13 @@
 @property (nonatomic) bool verifiesCertificates;
 
 /**
  * @brief Initializes the TLS socket with the specified TCP socket as its
  *	  underlying socket.
+ *
+ * The passed socket will become invalid, as the internal socket handle gets
+ * moved from the specified socket to the OFTLSSocket.
  *
  * @param socket The TCP socket to use as underlying socket
  */
 - (instancetype)initWithSocket: (OFTCPSocket *)socket;
 

Index: src/OFTLSSocket.m
==================================================================
--- src/OFTLSSocket.m
+++ src/OFTLSSocket.m
@@ -129,12 +129,12 @@
 
 	@try {
 		if ([socket isKindOfClass: [OFTLSSocket class]])
 			@throw [OFInvalidArgumentException exception];
 
-		if ((_socket = dup(socket->_socket)) == OFInvalidSocketHandle)
-			@throw [OFInitializationFailedException exception];
+		_socket = socket->_socket;
+		socket->_socket = OFInvalidSocketHandle;
 
 		_verifiesCertificates = true;
 	} @catch (id e) {
 		[self release];
 		@throw e;