@@ -117,22 +117,28 @@ func (s *DockerSuite) TestLogsTail(c *check.C) {

 	id := strings.TrimSpace(out)

 	dockerCmd(c, "wait", id)

-	out, _ = dockerCmd(c, "logs", "--tail", "5", id)

-

+	out, _ = dockerCmd(c, "logs", "--tail", "0", id)

 	lines := strings.Split(out, "\n")

+	c.Assert(lines, checker.HasLen, 1)

+	out, _ = dockerCmd(c, "logs", "--tail", "5", id)

+	lines = strings.Split(out, "\n")

 	c.Assert(lines, checker.HasLen, 6)

-	out, _ = dockerCmd(c, "logs", "--tail", "all", id)

+	out, _ = dockerCmd(c, "logs", "--tail", "99", id)

+	lines = strings.Split(out, "\n")

+	c.Assert(lines, checker.HasLen, 100)

+	out, _ = dockerCmd(c, "logs", "--tail", "all", id)

 	lines = strings.Split(out, "\n")

+	c.Assert(lines, checker.HasLen, testLen+1)

+	out, _ = dockerCmd(c, "logs", "--tail", "-1", id)

+	lines = strings.Split(out, "\n")

 	c.Assert(lines, checker.HasLen, testLen+1)

 	out, _, _ = dockerCmdWithStdoutStderr(c, "logs", "--tail", "random", id)

-

 	lines = strings.Split(out, "\n")

-

 	c.Assert(lines, checker.HasLen, testLen+1)

 }

@@ -44,7 +44,7 @@ func TailFile(f io.ReadSeeker, n int) ([][]byte, error) {

 			break

 		} else {

 			b = make([]byte, blockSize)

-			if _, err := f.Seek(step, os.SEEK_END); err != nil {

+			if _, err := f.Seek(left, os.SEEK_SET); err != nil {

 				return nil, err

 			}

 			if _, err := f.Read(b); err != nil {