diff --git a/README.rst b/README.rst
index f342da69..5911207a 100644
--- a/README.rst
+++ b/README.rst
@@ -287,10 +287,17 @@ Parameters
     Specify the line offset to print this bar (starting from 0)
     Automatic if unspecified.
     Useful to manage multiple bars at once (eg, from threads).
-* gui  : bool, optional  
-    WARNING: internal parameter - do not use.
-    Use tqdm_gui(...) instead. If set, will attempt to use
-    matplotlib animations for a graphical output [default: False].
+
+Extra CLI Options
+~~~~~~~~~~~~~~~~~
+
+* delim  : chr, optional  
+    Delimiting character [default: '\n']. Use '\0' for null.
+    N.B.: on Windows systems, Python converts '\n' to '\r\n'.
+* buf_size  : int, optional  
+    String buffer size in bytes [default: 256]
+    used when `delim` is specified.
+
 
 Returns
 ~~~~~~~
diff --git a/tqdm/_main.py b/tqdm/_main.py
index fa70bced..10a07cef 100644
--- a/tqdm/_main.py
+++ b/tqdm/_main.py
@@ -5,30 +5,42 @@ import re
 __all__ = ["main"]
 
 
+class TqdmArgumentError(ValueError):
+    pass
+
+
 def cast(val, typ):
+    # sys.stderr.write('\ndebug | `val:type`: `' + val + ':' + typ + '`.\n')
     if typ == 'bool':
-        # sys.stderr.write('\ndebug | `val:type`: `' + val + ':' + typ + '`.\n')
         if (val == 'True') or (val == ''):
             return True
         elif val == 'False':
             return False
         else:
-            raise ValueError(val + ' : ' + typ)
-
-    return eval(typ + '("' + val + '")')
+            raise TqdmArgumentError(val + ' : ' + typ)
+    try:
+        return eval(typ + '("' + val + '")')
+    except:
+        if (typ == 'chr'):
+            return chr(ord(eval('"' + val + '"')))
+        else:
+            raise TqdmArgumentError(val + ' : ' + typ)
 
 
-def posix_pipe(fin, fout, delim='\n', buf_size=4, callback=None):
+def posix_pipe(fin, fout, delim='\n', buf_size=256, callback=None):
     """
-    Returns
-    -------
-    out  : int. The number of items processed.
+    Params
+    ------
+    fin  : file with `read(buf_size : int)` method
+    fout  : file with `write` (and optionally `flush`) methods.
+    callback  : function(int), e.g.: `tqdm.update`
     """
-    if callback is None:
+    if callback is None:  # pragma: no cover
         def callback(i):
             pass
 
     buf = ''
+    tmp = ''
     # n = 0
     while True:
         tmp = fin.read(buf_size)
@@ -38,17 +50,20 @@ def posix_pipe(fin, fout, delim='\n', buf_size=4, callback=None):
             if buf:
                 fout.write(buf)
                 callback(1 + buf.count(delim))  # n += 1 + buf.count(delim)
-            getattr(fout, 'flush', lambda: None)()
+            getattr(fout, 'flush', lambda: None)()  # pragma: no cover
             return  # n
 
-        try:
-            i = tmp.index(delim)
-        except ValueError:
-            buf += tmp
-        else:
-            callback(1)  # n += 1
-            fout.write(buf + tmp[:i + len(delim)])
-            buf = tmp[i + len(delim):]
+        while True:
+            try:
+                i = tmp.index(delim)
+            except ValueError:
+                buf += tmp
+                break
+            else:
+                fout.write(buf + tmp[:i + len(delim)])
+                callback(1)  # n += 1
+                buf = ''
+                tmp = tmp[i + len(delim):]
 
 
 # RE_OPTS = re.compile(r' {8}(\S+)\s{2,}:\s*(str|int|float|bool)', flags=re.M)
@@ -59,17 +74,14 @@ UNSUPPORTED_OPTS = ('iterable', 'gui', 'out', 'file')
 
 # The 8 leading spaces are required for consistency
 CLI_EXTRA_DOC = """
-        CLI Options
-        -----------
-        delim  : int, optional
-            ascii ordinal for delimiting character [default: 10].
-            Example common values are given below.
-             0 : null
-             9 : \\t
-            10 : \\n
-            13 : \\r
+        Extra CLI Options
+        -----------------
+        delim  : chr, optional
+            Delimiting character [default: '\n']. Use '\0' for null.
+            N.B.: on Windows systems, Python converts '\n' to '\r\n'.
         buf_size  : int, optional
-            String buffer size [default: 4] used when `delim` is specified.
+            String buffer size in bytes [default: 256]
+            used when `delim` is specified.
 """
 
 
@@ -113,9 +125,9 @@ Options:
             tqdm_args[o[2:]] = cast(v, opt_types[o[2:]])
         # sys.stderr.write('\ndebug | args: ' + str(tqdm_args) + '\n')
 
-        delim = chr(tqdm_args.pop('delim', 10))
-        buf_size = tqdm_args.pop('buf_size', 4)
-        if delim == 10:
+        delim = tqdm_args.pop('delim', '\n')
+        buf_size = tqdm_args.pop('buf_size', 256)
+        if delim == '\n':
             for i in tqdm(sys.stdin, **tqdm_args):
                 sys.stdout.write(i)
         else:
diff --git a/tqdm/tests/tests_main.py b/tqdm/tests/tests_main.py
index f8eab8ba..b8d78264 100644
--- a/tqdm/tests/tests_main.py
+++ b/tqdm/tests/tests_main.py
@@ -3,7 +3,7 @@ import subprocess
 from tqdm import main
 from copy import deepcopy
 
-from tests_tqdm import with_setup, pretest, posttest, _range
+from tests_tqdm import with_setup, pretest, posttest, _range, closing, UnicodeIO
 
 
 def _sh(*cmd, **kwargs):
@@ -31,6 +31,13 @@ def test_main():
     except:
         pass
 
+    with closing(UnicodeIO()) as sys.stdin:
+        sys.argv = ['', '--desc', 'Test CLI delims',
+                    '--ascii', 'True', '--delim', r'\0', '--buf_size', '64']
+        sys.stdin.write('\0'.join(map(str, _range(int(1e3)))))
+        sys.stdin.seek(0)
+        main()
+
     sys.stdin = map(str, _range(int(1e3)))
     sys.argv = ['', '--desc', 'Test CLI pipes',
                 '--ascii', 'True', '--unit_scale', 'True']
diff --git a/tqdm/tests/tests_tqdm.py b/tqdm/tests/tests_tqdm.py
index 78e36b69..39ae8c3a 100644
--- a/tqdm/tests/tests_tqdm.py
+++ b/tqdm/tests/tests_tqdm.py
@@ -116,8 +116,11 @@ class UnicodeIO(IOBase):
         self.text += s
         self.cursor = len(self.text)
 
-    def read(self):
-        return self.text[self.cursor:]
+    def read(self, n=None):
+        _cur = self.cursor
+        self.cursor = len(self.text) if n is None \
+            else min(_cur + n, len(self.text))
+        return self.text[_cur:self.cursor]
 
     def getvalue(self):
         return self.text
@@ -1205,7 +1208,7 @@ def test_write():
                                      u'\r      ',
                                      u'\r\r      ',
                                      u'\rpos0 bar:  10%']
-            assert after_out == s+'\n'
+            assert after_out == s + '\n'
     # Restore stdout and stderr
     sys.stderr = stde
     sys.stdout = stdo