diff --git a/docs/source/configuration.rst b/docs/source/configuration.rst
index 4ea0e6b3..51a20595 100644
--- a/docs/source/configuration.rst
+++ b/docs/source/configuration.rst
@@ -472,11 +472,17 @@ Powerline script has a number of options controlling powerline behavior. Here
     example: ``{"K1": V1, "K2": V2}``) is recursively merged with the contents 
     of the file.
 
+    If ``VALUE`` is omitted then corresponding key will be removed from the 
+    configuration (if it was present).
+
 ``-t THEME_NAME.KEY.NESTED_KEY=VALUE`` or ``--theme_option=THEME_NAME.KEY.NESTED_KEY=VALUE``
     Overrides options from :file:`powerline/themes/{ext}/{THEME_NAME}.json`. 
     ``KEY.NESTED_KEY=VALUE`` is processed like described above, ``{ext}`` is the 
     first argument to powerline script. May be passed multiple times.
 
+    If ``VALUE`` is omitted then corresponding key will be removed from the 
+    configuration (if it was present).
+
 ``-p PATH`` or ``--config_path=PATH``
     Sets directory where configuration should be read from. If present, no 
     default locations are searched for configuration. No expansions are 
diff --git a/powerline/lib/__init__.py b/powerline/lib/__init__.py
index f8d831ac..b68b4830 100644
--- a/powerline/lib/__init__.py
+++ b/powerline/lib/__init__.py
@@ -3,6 +3,9 @@ from functools import wraps
 import json
 
 
+REMOVE_THIS_KEY = object()
+
+
 def wraps_saveargs(wrapped):
 	def dec(wrapper):
 		r = wraps(wrapped)(wrapper)
@@ -17,6 +20,8 @@ def mergedicts(d1, d2):
 	for k in d2:
 		if k in d1 and type(d1[k]) is dict and type(d2[k]) is dict:
 			mergedicts(d1[k], d2[k])
+		elif d2[k] is REMOVE_THIS_KEY:
+			d1.pop(k, None)
 		else:
 			d1[k] = d2[k]
 
@@ -45,7 +50,9 @@ def keyvaluesplit(s):
 	idx = s.index('=')
 	o = s[:idx]
 	rest = s[idx + 1:]
-	if rest[0] in '"{[0193456789' or rest in ('null', 'true', 'false'):
+	if not rest:
+		val = REMOVE_THIS_KEY
+	elif rest[0] in '"{[0193456789' or rest in ('null', 'true', 'false'):
 		val = json.loads(s[idx + 1:])
 	else:
 		val = rest
diff --git a/powerline/shell.py b/powerline/shell.py
index 677f2c49..4b817ae1 100644
--- a/powerline/shell.py
+++ b/powerline/shell.py
@@ -7,8 +7,7 @@ from powerline.lib import mergedicts, parsedotval
 def mergeargs(argvalue):
 	if not argvalue:
 		return None
-	argvalue = iter(argvalue)
-	r = dict([next(argvalue)])
+	r = {}
 	for subval in argvalue:
 		mergedicts(r, dict([subval]))
 	return r
diff --git a/tests/test_cmdline.py b/tests/test_cmdline.py
index c330da36..91f27adb 100644
--- a/tests/test_cmdline.py
+++ b/tests/test_cmdline.py
@@ -94,6 +94,8 @@ class TestParser(TestCase):
 					'renderer_arg': {'smth': {'abc': 'def'}},
 				}),
 				(['shell', '-R', 'arg=true'], {'ext': ['shell'], 'renderer_arg': {'arg': True}}),
+				(['shell', '-R', 'arg=true', '-R', 'arg='], {'ext': ['shell'], 'renderer_arg': {}}),
+				(['shell', '-R', 'arg='], {'ext': ['shell'], 'renderer_arg': {}}),
 				(['shell', '-t', 'default.segment_info={"hostname": {}}'], {
 					'ext': ['shell'],
 					'theme_option': {
diff --git a/tests/test_lib.py b/tests/test_lib.py
index f4da57d2..6c306615 100644
--- a/tests/test_lib.py
+++ b/tests/test_lib.py
@@ -1,7 +1,7 @@
 # vim:fileencoding=utf-8:noet
 from __future__ import division
 
-from powerline.lib import mergedicts, add_divider_highlight_group
+from powerline.lib import mergedicts, add_divider_highlight_group, REMOVE_THIS_KEY
 from powerline.lib.humanize_bytes import humanize_bytes
 from powerline.lib.vcs import guess
 from powerline.lib.threaded import ThreadedSegment, KwThreadedSegment
@@ -354,6 +354,8 @@ class TestLib(TestCase):
 		self.assertEqual(d, {'abc': {'def': {'ghi': 'jkl'}}})
 		mergedicts(d, {'abc': {'mno': 'pqr'}})
 		self.assertEqual(d, {'abc': {'def': {'ghi': 'jkl'}, 'mno': 'pqr'}})
+		mergedicts(d, {'abc': {'def': REMOVE_THIS_KEY}})
+		self.assertEqual(d, {'abc': {'mno': 'pqr'}})
 
 	def test_add_divider_highlight_group(self):
 		def decorated_function_name(**kwargs):