diff --git a/docker.v b/docker.v
index 2963f0d..97cd24a 100644
--- a/docker.v
+++ b/docker.v
@@ -24,8 +24,8 @@ mut:
 }
 
 // new_conn creates a new connection to the Docker daemon.
-pub fn new_conn() ?&DockerConn {
-	s := unix.connect_stream(docker.socket)?
+pub fn new_conn() !&DockerConn {
+	s := unix.connect_stream(docker.socket)!
 
 	d := &DockerConn{
 		socket: s
@@ -36,27 +36,27 @@ pub fn new_conn() ?&DockerConn {
 }
 
 // close closes the underlying socket connection.
-pub fn (mut d DockerConn) close() ? {
-	d.socket.close()?
+pub fn (mut d DockerConn) close() ! {
+	d.socket.close()!
 }
 
 // send_request sends an HTTP request without body.
-fn (mut d DockerConn) send_request(method http.Method, url_str string) ? {
-	url := urllib.parse('/$docker.api_version$url_str')?
+fn (mut d DockerConn) send_request(method http.Method, url_str string) ! {
+	url := urllib.parse('/$docker.api_version$url_str')!
 	req := '$method $url.request_uri() HTTP/1.1\nHost: localhost\n\n'
 
-	d.socket.write_string(req)?
+	d.socket.write_string(req)!
 
 	// When starting a new request, the reader needs to be reset.
 	d.reader = io.new_buffered_reader(reader: d.socket)
 }
 
 // send_request_with_body sends an HTTP request with the given body.
-fn (mut d DockerConn) send_request_with_body(method http.Method, url_str string, content_type string, body string) ? {
-	url := urllib.parse('/$docker.api_version$url_str')?
+fn (mut d DockerConn) send_request_with_body(method http.Method, url_str string, content_type string, body string) ! {
+	url := urllib.parse('/$docker.api_version$url_str')!
 	req := '$method $url.request_uri() HTTP/1.1\nHost: localhost\nContent-Type: $content_type\nContent-Length: $body.len\n\n$body\n\n'
 
-	d.socket.write_string(req)?
+	d.socket.write_string(req)!
 
 	// When starting a new request, the reader needs to be reset.
 	d.reader = io.new_buffered_reader(reader: d.socket)
@@ -64,7 +64,7 @@ fn (mut d DockerConn) send_request_with_body(method http.Method, url_str string,
 
 // send_request_with_json<T> is a convenience wrapper around
 // send_request_with_body that encodes the input as JSON.
-fn (mut d DockerConn) send_request_with_json<T>(method http.Method, url_str string, data &T) ? {
+fn (mut d DockerConn) send_request_with_json<T>(method http.Method, url_str string, data &T) ! {
 	body := json.encode(data)
 
 	return d.send_request_with_body(method, url_str, 'application/json', body)
@@ -74,17 +74,17 @@ fn (mut d DockerConn) send_request_with_json<T>(method http.Method, url_str stri
 // '\r\n\r\n', after which it parses the response as an HTTP response.
 // Importantly, this function never consumes the reader past the HTTP
 // separator, so the body can be read fully later on.
-fn (mut d DockerConn) read_response_head() ?http.Response {
+fn (mut d DockerConn) read_response_head() !http.Response {
 	mut res := []u8{}
 
-	util.read_until_separator(mut d.reader, mut res, docker.http_separator)?
+	util.read_until_separator(mut d.reader, mut res, docker.http_separator)!
 
 	return http.parse_response(res.bytestr())
 }
 
 // read_response_body reads `length` bytes from the stream. It can be used when
 // the response encoding isn't chunked to fully read it.
-fn (mut d DockerConn) read_response_body(length int) ?string {
+fn (mut d DockerConn) read_response_body(length int) !string {
 	if length == 0 {
 		return ''
 	}
@@ -96,7 +96,7 @@ fn (mut d DockerConn) read_response_body(length int) ?string {
 	for builder.len < length {
 		c = d.reader.read(mut buf) or { break }
 
-		builder.write(buf[..c])?
+		builder.write(buf[..c])!
 	}
 
 	return builder.str()
@@ -105,34 +105,34 @@ fn (mut d DockerConn) read_response_body(length int) ?string {
 // read_response is a convenience function which always consumes the entire
 // response & returns it. It should only be used when we're certain that the
 // result isn't too large.
-fn (mut d DockerConn) read_response() ?(http.Response, string) {
-	head := d.read_response_head()?
+fn (mut d DockerConn) read_response() !(http.Response, string) {
+	head := d.read_response_head()!
 
 	if head.header.get(http.CommonHeader.transfer_encoding) or { '' } == 'chunked' {
 		mut builder := strings.new_builder(1024)
 		mut body := d.get_chunked_response_reader()
 
-		util.reader_to_writer(mut body, mut builder)?
+		util.reader_to_writer(mut body, mut builder)!
 
 		return head, builder.str()
 	}
 
-	content_length := head.header.get(http.CommonHeader.content_length)?.int()
-	res := d.read_response_body(content_length)?
+	content_length := head.header.get(http.CommonHeader.content_length)!.int()
+	res := d.read_response_body(content_length)!
 
 	return head, res
 }
 
-fn (mut d DockerConn) read_json_response<T>() ?T {
-	head, body := d.read_response()?
+fn (mut d DockerConn) read_json_response<T>() !T {
+	head, body := d.read_response()!
 
 	if head.status_code < 200 || head.status_code > 300 {
-		data := json.decode(DockerError, body)?
+		data := json.decode(DockerError, body)!
 
 		return docker_error(head.status_code, data.message)
 	}
 
-	mut data := json.decode(T, body)?
+	mut data := json.decode(T, body)!
 
 	//$for field in T.fields {
 	//$if field.typ is time.Time {
diff --git a/stream.v b/stream.v
index 001f4b3..39ab42a 100644
--- a/stream.v
+++ b/stream.v
@@ -25,11 +25,11 @@ pub fn new_chunked_response_reader(reader io.BufferedReader) &ChunkedResponseRea
 }
 
 // read satisfies the io.Reader interface.
-pub fn (mut r ChunkedResponseReader) read(mut buf []u8) ?int {
+pub fn (mut r ChunkedResponseReader) read(mut buf []u8) !int {
 	if r.bytes_left_in_chunk == 0 {
 		// An io.BufferedReader always returns none if its stream has
 		// ended.
-		r.bytes_left_in_chunk = r.read_chunk_size()?
+		r.bytes_left_in_chunk = r.read_chunk_size()!
 	}
 
 	mut c := 0
@@ -37,9 +37,9 @@ pub fn (mut r ChunkedResponseReader) read(mut buf []u8) ?int {
 	// Make sure we don't read more than we can safely read. This is to avoid
 	// the underlying reader from becoming out of sync with our parsing:
 	if buf.len > r.bytes_left_in_chunk {
-		c = r.reader.read(mut buf[..r.bytes_left_in_chunk])?
+		c = r.reader.read(mut buf[..r.bytes_left_in_chunk])!
 	} else {
-		c = r.reader.read(mut buf)?
+		c = r.reader.read(mut buf)!
 	}
 
 	r.bytes_left_in_chunk -= u64(c)
@@ -50,21 +50,21 @@ pub fn (mut r ChunkedResponseReader) read(mut buf []u8) ?int {
 // read_chunk_size advances the reader & reads the size of the next HTTP chunk.
 // This function should only be called if the previous chunk has been
 // completely consumed.
-fn (mut r ChunkedResponseReader) read_chunk_size() ?u64 {
+fn (mut r ChunkedResponseReader) read_chunk_size() !u64 {
 	if r.started {
 		mut buf := []u8{len: 2}
 
 		// Each chunk ends with a `\r\n` which we want to skip first
-		r.reader.read(mut buf)?
+		r.reader.read(mut buf)!
 	}
 
 	r.started = true
 
 	mut res := []u8{}
-	util.read_until_separator(mut r.reader, mut res, http_chunk_separator)?
+	util.read_until_separator(mut r.reader, mut res, http_chunk_separator)!
 
 	// The length of the next chunk is provided as a hexadecimal
-	mut num_data := hex.decode(res#[..-2].bytestr())?
+	mut num_data := hex.decode(res#[..-2].bytestr())!
 
 	for num_data.len < 8 {
 		num_data.insert(0, 0)
@@ -75,7 +75,7 @@ fn (mut r ChunkedResponseReader) read_chunk_size() ?u64 {
 	// This only occurs for the very last chunk, which always reports a size of
 	// 0.
 	if num == 0 {
-		return none
+		return error('end of stream')
 	}
 
 	return num
@@ -100,17 +100,17 @@ pub fn new_stream_format_reader(reader ChunkedResponseReader) &StreamFormatReade
 }
 
 // read satisfies the io.Reader interface.
-pub fn (mut r StreamFormatReader) read(mut buf []u8) ?int {
+pub fn (mut r StreamFormatReader) read(mut buf []u8) !int {
 	if r.bytes_left_in_chunk == 0 {
-		r.bytes_left_in_chunk = r.read_chunk_size()?
+		r.bytes_left_in_chunk = r.read_chunk_size()!
 	}
 
 	mut c := 0
 
 	if buf.len > r.bytes_left_in_chunk {
-		c = r.reader.read(mut buf[..r.bytes_left_in_chunk])?
+		c = r.reader.read(mut buf[..r.bytes_left_in_chunk])!
 	} else {
-		c = r.reader.read(mut buf)?
+		c = r.reader.read(mut buf)!
 	}
 
 	r.bytes_left_in_chunk -= u32(c)
@@ -120,15 +120,15 @@ pub fn (mut r StreamFormatReader) read(mut buf []u8) ?int {
 
 // read_chunk_size advances the reader & reads the header bytes for the length
 // of the next chunk.
-fn (mut r StreamFormatReader) read_chunk_size() ?u32 {
+fn (mut r StreamFormatReader) read_chunk_size() !u32 {
 	mut buf := []u8{len: 8}
 
-	r.reader.read(mut buf)?
+	r.reader.read(mut buf)!
 
 	num := binary.big_endian_u32(buf[4..])
 
 	if num == 0 {
-		return none
+		return error('end of stream')
 	}
 
 	return num
diff --git a/util/util.v b/util/util.v
index 412e39c..1181480 100644
--- a/util/util.v
+++ b/util/util.v
@@ -3,7 +3,7 @@ module util
 import io
 
 // reader_to_writer tries to consume the entire reader & write it to the writer.
-pub fn reader_to_writer(mut reader io.Reader, mut writer io.Writer) ? {
+pub fn reader_to_writer(mut reader io.Reader, mut writer io.Writer) ! {
 	mut buf := []u8{len: 10 * 1024}
 
 	for {
@@ -39,11 +39,11 @@ pub fn match_array_in_array<T>(a1 []T, a2 []T) int {
 
 // read_until_separator consumes an io.Reader until it encounters some
 // separator array. The data read is stored inside the provided res array.
-pub fn read_until_separator(mut reader io.Reader, mut res []u8, sep []u8) ? {
+pub fn read_until_separator(mut reader io.Reader, mut res []u8, sep []u8) ! {
 	mut buf := []u8{len: sep.len}
 
 	for {
-		c := reader.read(mut buf)?
+		c := reader.read(mut buf)!
 		res << buf[..c]
 
 		match_len := match_array_in_array(buf[..c], sep)
@@ -54,7 +54,7 @@ pub fn read_until_separator(mut reader io.Reader, mut res []u8, sep []u8) ? {
 
 		if match_len > 0 {
 			match_left := sep.len - match_len
-			c2 := reader.read(mut buf[..match_left])?
+			c2 := reader.read(mut buf[..match_left])!
 			res << buf[..c2]
 
 			if buf[..c2] == sep[match_len..] {