Index: src/OFFile.m
==================================================================
--- src/OFFile.m
+++ src/OFFile.m
@@ -394,42 +394,58 @@
 {
 	if (_handle == OF_INVALID_FILE_HANDLE)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 #if defined(OF_WINDOWS)
+	int bytesWritten;
+
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (write(_handle, buffer, (int)length) != (int)length)
+	if ((bytesWritten = write(_handle, buffer, (int)length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errno];
 #elif defined(OF_MORPHOS)
+	LONG bytesWritten;
+
 	if (length > LONG_MAX)
 		@throw [OFOutOfRangeException exception];
 
 	if (_handle->append) {
 		if (Seek64(_handle->handle, 0, OFFSET_END) == -1)
 			@throw [OFWriteFailedException
 			    exceptionWithObject: self
 				requestedLength: length
+				   bytesWritten: 0
 					  errNo: EIO];
 	}
 
-	if (Write(_handle->handle, (void *)buffer, length) != (LONG)length)
+	if ((bytesWritten = Write(_handle->handle, (void *)buffer, length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: EIO];
 #else
+	ssize_t bytesWritten;
+
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (write(_handle, buffer, length) != (ssize_t)length)
+	if ((bytesWritten = write(_handle, buffer, length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errno];
 #endif
+
+	if ((size_t)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 - (of_offset_t)lowlevelSeekToOffset: (of_offset_t)offset
 			     whence: (int)whence
 {

Index: src/OFProcess.m
==================================================================
--- src/OFProcess.m
+++ src/OFProcess.m
@@ -486,41 +486,51 @@
 
 - (void)lowlevelWriteBuffer: (const void *)buffer
 		     length: (size_t)length
 {
 #ifndef OF_WINDOWS
+	ssize_t bytesWritten;
+
 	if (_writePipe[1] == -1)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (write(_writePipe[1], buffer, length) != (ssize_t)length)
+	if ((bytesWritten = write(_writePipe[1], buffer, length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errno];
 #else
-	DWORD ret;
+	DWORD bytesWritten;
 
 	if (length > UINT32_MAX)
 		@throw [OFOutOfRangeException exception];
 
 	if (_writePipe[1] == NULL)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
-	if (!WriteFile(_writePipe[1], buffer, (DWORD)length, &ret, NULL) ||
-	    ret != (DWORD)length) {
+	if (!WriteFile(_writePipe[1], buffer, (DWORD)length, &bytesWritten,
+	    NULL)) {
 		int errNo = EIO;
 
 		if (GetLastError() == ERROR_BROKEN_PIPE)
 			errNo = EPIPE;
 
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errNo];
 	}
 #endif
+
+	if ((size_t)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 - (int)fileDescriptorForReading
 {
 #ifndef OF_WINDOWS

Index: src/OFStdIOStream.m
==================================================================
--- src/OFStdIOStream.m
+++ src/OFStdIOStream.m
@@ -224,38 +224,53 @@
 #ifndef OF_MORPHOS
 	if (_fd == -1)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 # ifndef OF_WINDOWS
+	ssize_t bytesWritten;
+
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (write(_fd, buffer, length) != (ssize_t)length)
+	if ((bytesWritten = write(_fd, buffer, length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errno];
 # else
+	int bytesWritten;
+
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (write(_fd, buffer, (int)length) != (int)length)
+	if ((bytesWritten = write(_fd, buffer, (int)length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: errno];
 # endif
 #else
+	LONG bytesWritten;
+
 	if (_handle == 0)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (Write(_handle, (void *)buffer, length) != (LONG)length)
+	if ((bytesWritten = Write(_handle, (void *)buffer, length)) < 0)
 		@throw [OFWriteFailedException exceptionWithObject: self
 						   requestedLength: length
+						      bytesWritten: 0
 							     errNo: EIO];
 #endif
+
+	if ((size_t)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 #if !defined(OF_WINDOWS) && !defined(OF_MORPHOS)
 - (int)fileDescriptorForReading
 {

Index: src/OFStdIOStream_Win32Console.m
==================================================================
--- src/OFStdIOStream_Win32Console.m
+++ src/OFStdIOStream_Win32Console.m
@@ -231,11 +231,11 @@
 	if (_incompleteUTF8SurrogateLen > 0) {
 		of_unichar_t c;
 		char16_t UTF16[2];
 		ssize_t UTF8Len;
 		size_t toCopy;
-		DWORD UTF16Len, written;
+		DWORD UTF16Len, bytesWritten;
 
 		UTF8Len = -of_string_utf8_decode(
 		    _incompleteUTF8Surrogate, _incompleteUTF8SurrogateLen, &c);
 
 		OF_ENSURE(UTF8Len > 0);
@@ -269,25 +269,33 @@
 				UTF16[0] = c;
 				UTF16Len = 1;
 			}
 		}
 
-		if (!WriteConsoleW(_handle, UTF16, UTF16Len, &written, NULL) ||
-		    written != UTF16Len)
+		if (!WriteConsoleW(_handle, UTF16, UTF16Len, &bytesWritten,
+		    NULL))
+			@throw [OFWriteFailedException
+			    exceptionWithObject: self
+				requestedLength: UTF16Len * 2
+				   bytesWritten: 0
+					  errNo: EIO];
+
+		if (bytesWritten != UTF16Len)
 			@throw [OFWriteFailedException
 			    exceptionWithObject: self
 				requestedLength: UTF16Len * 2
-					  errNo: EIO];
+				   bytesWritten: bytesWritten * 2
+					  errNo: 0];
 
 		_incompleteUTF8SurrogateLen = 0;
 		i += toCopy;
 	}
 
 	tmp = [self allocMemoryWithSize: sizeof(char16_t)
 				  count: length * 2];
 	@try {
-		DWORD written;
+		DWORD bytesWritten;
 
 		while (i < length) {
 			of_unichar_t c;
 			ssize_t UTF8Len;
 
@@ -321,16 +329,23 @@
 		}
 
 		if (j > UINT32_MAX)
 			@throw [OFOutOfRangeException exception];
 
-		if (!WriteConsoleW(_handle, tmp, (DWORD)j, &written, NULL) ||
-		    written != j)
+		if (!WriteConsoleW(_handle, tmp, (DWORD)j, &bytesWritten, NULL))
+			@throw [OFWriteFailedException
+			    exceptionWithObject: self
+				requestedLength: j * 2
+				   bytesWritten: 0
+					  errNo: EIO];
+
+		if (bytesWritten != j)
 			@throw [OFWriteFailedException
 			    exceptionWithObject: self
 				requestedLength: j * 2
-					  errNo: EIO];
+				   bytesWritten: bytesWritten * 2
+					  errNo: 0];
 	} @finally {
 		[self freeMemory: tmp];
 	}
 }
 @end

Index: src/OFStreamSocket.m
==================================================================
--- src/OFStreamSocket.m
+++ src/OFStreamSocket.m
@@ -92,28 +92,40 @@
 {
 	if (_socket == INVALID_SOCKET)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 #ifndef OF_WINDOWS
+	ssize_t bytesWritten;
+
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (send(_socket, buffer, length, 0) != (ssize_t)length)
+	if ((bytesWritten = send(_socket, buffer, length, 0)) < 0)
 		@throw [OFWriteFailedException
 		    exceptionWithObject: self
 			requestedLength: length
+			   bytesWritten: 0
 				  errNo: of_socket_errno()];
 #else
+	int bytesWritten;
+
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (send(_socket, buffer, (int)length, 0) != (int)length)
+	if ((bytesWritten = send(_socket, buffer, (int)length, 0)) < 0)
 		@throw [OFWriteFailedException
 		    exceptionWithObject: self
 			requestedLength: length
+			   bytesWritten: 0
 				  errNo: of_socket_errno()];
 #endif
+
+	if ((size_t)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 #ifdef OF_WINDOWS
 - (void)setBlocking: (bool)enable
 {

Index: src/OFTCPSocket+SOCKS5.m
==================================================================
--- src/OFTCPSocket+SOCKS5.m
+++ src/OFTCPSocket+SOCKS5.m
@@ -33,15 +33,28 @@
 
 static void
 send_or_exception(OFTCPSocket *self, of_socket_t socket, char *buffer,
     int length)
 {
-	if (send(socket, (const void *)buffer, length, 0) != length)
+#ifndef OF_WINDOWS
+	ssize_t bytesWritten;
+#else
+	int bytesWritten;
+#endif
+
+	if ((bytesWritten = send(socket, (const void *)buffer, length, 0)) < 0)
 		@throw [OFWriteFailedException
 		    exceptionWithObject: self
 			requestedLength: length
+			   bytesWritten: 0
 				  errNo: of_socket_errno()];
+
+	if ((int)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 static void
 recv_exact(OFTCPSocket *self, of_socket_t socket, char *buffer, int length)
 {

Index: src/OFUDPSocket.m
==================================================================
--- src/OFUDPSocket.m
+++ src/OFUDPSocket.m
@@ -586,32 +586,43 @@
 {
 	if (_socket == INVALID_SOCKET)
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 #ifndef OF_WINDOWS
+	ssize_t bytesWritten;
+
 	if (length > SSIZE_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (sendto(_socket, buffer, length, 0,
-	    (struct sockaddr *)&receiver->address,
-	    receiver->length) != (ssize_t)length)
+	if ((bytesWritten = sendto(_socket, buffer, length, 0,
+	    (struct sockaddr *)&receiver->address, receiver->length)) < 0)
 		@throw [OFWriteFailedException
 		    exceptionWithObject: self
 			requestedLength: length
+			   bytesWritten: 0
 				  errNo: of_socket_errno()];
 #else
+	int bytesWritten;
+
 	if (length > INT_MAX)
 		@throw [OFOutOfRangeException exception];
 
-	if (sendto(_socket, buffer, (int)length, 0,
+	if ((bytesWritten = sendto(_socket, buffer, (int)length, 0,
 	    (struct sockaddr *)&receiver->address,
-	    receiver->length) != (int)length)
+	    receiver->length)) < 0)
 		@throw [OFWriteFailedException
 		    exceptionWithObject: self
 			requestedLength: length
+			   bytesWritten: 0
 				  errNo: of_socket_errno()];
 #endif
+
+	if ((size_t)bytesWritten != length)
+		@throw [OFWriteFailedException exceptionWithObject: self
+						   requestedLength: length
+						      bytesWritten: bytesWritten
+							     errNo: 0];
 }
 
 - (void)cancelAsyncRequests
 {
 	[OFRunLoop of_cancelAsyncRequestsForObject: self];

Index: src/exceptions/OFWriteFailedException.h
==================================================================
--- src/exceptions/OFWriteFailedException.h
+++ src/exceptions/OFWriteFailedException.h
@@ -23,8 +23,59 @@
  *	  OFWriteFailedException.h ObjFW/OFWriteFailedException.h
  *
  * @brief An exception indicating that writing to an object failed.
  */
 @interface OFWriteFailedException: OFReadOrWriteFailedException
+{
+	size_t _bytesWritten;
+}
+
+/*!
+ * The number of bytes already written before the write failed.
+ *
+ * This can be used to make sure that a retry does not write data already
+ * written before.
+ */
+@property (readonly, nonatomic) size_t bytesWritten;
+
++ (instancetype)exceptionWithObject: (id)object
+		    requestedLength: (size_t)requestedLength
+			      errNo: (int)errNo OF_UNAVAILABLE;
+
+/*!
+ * @brief Creates a new, autoreleased write failed exception.
+ *
+ * @param object The object from which reading or to which writing failed
+ * @param requestedLength The requested length of the data that could not be
+ *			  read / written
+ * @param bytesWritten The amount of bytes already written before the write
+ *		       failed
+ * @param errNo The errno of the error that occurred
+ * @return A new, autoreleased write failed exception
+ */
++ (instancetype)exceptionWithObject: (id)object
+		    requestedLength: (size_t)requestedLength
+		       bytesWritten: (size_t)bytesWritten
+			      errNo: (int)errNo;
+
+-  initWithObject: (id)object
+  requestedLength: (size_t)requestedLength
+	    errNo: (int)errNo OF_UNAVAILABLE;
+
+/*!
+ * @brief Initializes an already allocated write failed exception.
+ *
+ * @param object The object from which reading or to which writing failed
+ * @param requestedLength The requested length of the data that could not be
+ *			  read / written
+ * @param bytesWritten The amount of bytes already written before the write
+ *		       failed
+ * @param errNo The errno of the error that occurred
+ * @return A new open file failed exception
+ */
+-  initWithObject: (id)object
+  requestedLength: (size_t)requestedLength
+     bytesWritten: (size_t)bytesWritten
+	    errNo: (int)errNo OF_DESIGNATED_INITIALIZER;
 @end
 
 OF_ASSUME_NONNULL_END

Index: src/exceptions/OFWriteFailedException.m
==================================================================
--- src/exceptions/OFWriteFailedException.m
+++ src/exceptions/OFWriteFailedException.m
@@ -18,12 +18,57 @@
 
 #import "OFWriteFailedException.h"
 #import "OFString.h"
 
 @implementation OFWriteFailedException
+@synthesize bytesWritten = _bytesWritten;
+
++ (instancetype)exceptionWithObject: (id)object
+		    requestedLength: (size_t)requestedLength
+			      errNo: (int)errNo
+{
+	return [[[self alloc] initWithObject: object
+			     requestedLength: requestedLength
+				       errNo: errNo] autorelease];
+}
+
++ (instancetype)exceptionWithObject: (id)object
+		    requestedLength: (size_t)requestedLength
+		       bytesWritten: (size_t)bytesWritten
+			      errNo: (int)errNo
+{
+	return [[[self alloc] initWithObject: object
+			     requestedLength: requestedLength
+				bytesWritten: bytesWritten
+				       errNo: errNo] autorelease];
+}
+
+-  initWithObject: (id)object
+  requestedLength: (size_t)requestedLength
+	    errNo: (int)errNo
+{
+	OF_INVALID_INIT_METHOD
+}
+
+-  initWithObject: (id)object
+  requestedLength: (size_t)requestedLength
+     bytesWritten: (size_t)bytesWritten
+	    errNo: (int)errNo
+{
+	self = [super initWithObject: object
+		     requestedLength: requestedLength
+			       errNo: errNo];
+
+	_bytesWritten = bytesWritten;
+
+	return self;
+}
+
 - (OFString *)description
 {
 	return [OFString stringWithFormat:
-	    @"Failed to write %zu bytes to an object of type %@: %@",
-	    _requestedLength, [_object class], of_strerror(_errNo)];
+	    @"Failed to write %zu bytes (after %zu bytes written)  to an "
+	    @"object of type %@: %@",
+	    _requestedLength, _bytesWritten, [_object class],
+	    of_strerror(_errNo)];
 }
 @end