diff --git a/conventions/changelog.py b/conventions/changelog.py
index da9e411..42bbade 100644
--- a/conventions/changelog.py
+++ b/conventions/changelog.py
@@ -1,11 +1,12 @@
 from os import system
 from utils import get_text
-from utils import change_if_none
+from utils import sanitize_as_empty_string
+from utils import gen_co_author
 
 
-def changelog_convention(co_author=''):
+def changelog_convention(co_author):
     tag, msg = get_text()
     tag = tag.upper()
-    co_author = change_if_none(co_author)
-    composed_message = """%s: %s\n\nCo-authored-by: """ % (tag, msg)
-    system("git commit -m '%s%s'" % (composed_message, co_author))
+    composed_message = "%s: %s\n" % (tag, msg)
+    composed_message += gen_co_author(co_author)
+    system("git commit -m '%s'" % composed_message)
diff --git a/conventions/karma_angular.py b/conventions/karma_angular.py
index 6dabb87..55260e4 100644
--- a/conventions/karma_angular.py
+++ b/conventions/karma_angular.py
@@ -1,12 +1,15 @@
 from os import system
 from utils import get_text
-from utils import change_if_none
+from utils import sanitize_as_empty_string
+from utils import gen_co_author
 
 
-def angular_convention(co_author=''):
+def angular_convention(co_author):
     tag, msg, context = get_text(context=True)
     tag = tag.lower()
-    co_author = change_if_none(co_author)
-    composed_message = """%s(%s): %s\n\nCo-authored-by:
-""" % (tag, context, msg)
-    system('git commit -m "%s%s"' % (composed_message, co_author))
+    co_author = sanitize_as_empty_string(co_author)
+    if context is '':
+        composed_message = composed_message = "%s: %s\n" % (tag, msg)
+    composed_message = "%s(%s): %s\n" % (tag, context, msg)
+    composed_message += gen_co_author(co_author)
+    system('git commit -m "%s"' % composed_message)
diff --git a/conventions/no_convention.py b/conventions/no_convention.py
index 9109933..6b45a23 100644
--- a/conventions/no_convention.py
+++ b/conventions/no_convention.py
@@ -1,9 +1,10 @@
 from os import system
-from utils import change_if_none
+from utils import sanitize_as_empty_string
+from utils import gen_co_author
 
 
-def just_message(co_author=''):
+def just_message(co_author):
     msg = str(input("commit message: "))
-    co_author = change_if_none(co_author)
-    composed = """%s\n\nCo-authored-by: """ % msg.capitalize()
-    system("git commit -m '%s%s'" % (composed, co_author))
+    composed = "%s\n" % msg.capitalize()
+    composed += gen_co_author(co_author)
+    system("git commit -m '%s'" % composed)
diff --git a/conventions/symphony_cmf.py b/conventions/symphony_cmf.py
index ed4a4f7..f6bd76e 100644
--- a/conventions/symphony_cmf.py
+++ b/conventions/symphony_cmf.py
@@ -1,11 +1,12 @@
 from os import system
 from utils import get_text
-from utils import change_if_none
+from utils import sanitize_as_empty_string
+from utils import gen_co_author
 
 
-def symphony_convention(co_author=''):
+def symphony_convention(co_author):
     tag, msg = get_text()
     tag = tag.capitalize()
-    co_author = change_if_none(co_author)
-    composed = """[%s] %s\n\nCo-authored-by: """ % (tag, msg)
-    system("git commit -m '%s%s'" % (composed, co_author))
+    composed = "[%s] %s\n" % (tag, msg)
+    composed += gen_co_author(co_author)
+    system("git commit -m '%s'" % composed)
diff --git a/test/test_utils.py b/test/test_utils.py
index d48075f..634b5c1 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -37,14 +37,24 @@ def mock_input(s):
         raise AssertionError()
 
 
-def test_change_if_none():
+def test_sanitize_as_empty_string():
     string = 'asopdfha'
     string2 = None
-    string = utils.change_if_none(string)
-    string2 = utils.change_if_none(string2)
+    string = utils.sanitize_as_empty_string(string)
+    string2 = utils.sanitize_as_empty_string(string2)
     if not (string == 'asopdfha' and string2 == ''):
         raise AssertionError()
 
+
+def test_gen_co_author():
+    arg = utils.gen_co_author('kiryto <black.swordsman@aincrad.com>')
+    if not arg == "Co-authored-by: kiryto <black.swordsman@aincrad.com>":
+        raise AssertionError()
+
+    arg2 = utils.gen_co_author('')
+    if not arg2 == '':
+        raise AssertionError()
+
 # FIXME
 # def test_create_file(tmpdir):
 #     test_file = tmpdir.mkdir('test').join('commiter.yml')
diff --git a/utils.py b/utils.py
index be085c0..7371e88 100644
--- a/utils.py
+++ b/utils.py
@@ -3,6 +3,7 @@
 
 supported_conventions = [
     "angular",
+    "karma",
     "changelog",
     "symphony",
     "message",
@@ -23,7 +24,7 @@ def get_text(context=False):
     if context:
         tag = str(input("type the tag: "))
         msg = str(input("type the commit message: ")).lower()
-        context = str(input('type the context: ')).lower()
+        context = str(input('type the context: ') or '').lower()
         return tag, msg, context
     else:
         tag = str(input("type the tag: "))
@@ -31,6 +32,12 @@ def get_text(context=False):
         return tag, msg
 
 
+def gen_co_author(co_author):
+    if co_author is '':
+        return ''
+    return "Co-authored-by: %s" % co_author
+
+
 def create_file(convention_name, dont_create=False):
     if not dont_create:
         data = dict(
@@ -62,7 +69,7 @@ def parser_cli():
     return parser
 
 
-def change_if_none(string):
+def sanitize_as_empty_string(string):
     if string is None:
         return ''
     return string