diff --git a/tests/rules/test_git_diff_staged.py b/tests/rules/test_git_diff_staged.py
index a4c62a37..364cb267 100644
--- a/tests/rules/test_git_diff_staged.py
+++ b/tests/rules/test_git_diff_staged.py
@@ -3,7 +3,9 @@ from thefuck.rules.git_diff_staged import match, get_new_command
 from tests.utils import Command
 
 
-@pytest.mark.parametrize('command', [Command(script='git diff')])
+@pytest.mark.parametrize('command', [
+    Command(script='git diff foo'),
+    Command(script='git diff')])
 def test_match(command):
     assert match(command, None)
 
@@ -18,6 +20,7 @@ def test_not_match(command):
 
 
 @pytest.mark.parametrize('command, new_command', [
-    (Command('git diff'), 'git diff --staged')])
+    (Command('git diff'), 'git diff --staged'),
+    (Command('git diff foo'), 'git diff --staged foo')])
 def test_get_new_command(command, new_command):
     assert get_new_command(command, None) == new_command
diff --git a/tests/rules/test_sudo.py b/tests/rules/test_sudo.py
index af2de9f2..171088e3 100644
--- a/tests/rules/test_sudo.py
+++ b/tests/rules/test_sudo.py
@@ -11,6 +11,7 @@ from tests.utils import Command
     ('need to be root', ''),
     ('need root', ''),
     ('must be root', ''),
+    ('You don\'t have access to the history DB.', ''),
     ('', "error: [Errno 13] Permission denied: '/usr/local/lib/python2.7/dist-packages/ipaddr.py'")])
 def test_match(stderr, stdout):
     assert match(Command(stderr=stderr, stdout=stdout), None)
diff --git a/thefuck/rules/git_diff_staged.py b/thefuck/rules/git_diff_staged.py
index a35234e4..c879cf40 100644
--- a/thefuck/rules/git_diff_staged.py
+++ b/thefuck/rules/git_diff_staged.py
@@ -10,4 +10,4 @@ def match(command, settings):
 
 @utils.git_support
 def get_new_command(command, settings):
-    return '{} --staged'.format(command.script)
+    return command.script.replace(' diff', ' diff --staged')
diff --git a/thefuck/rules/sudo.py b/thefuck/rules/sudo.py
index 31687549..97b7a5e0 100644
--- a/thefuck/rules/sudo.py
+++ b/thefuck/rules/sudo.py
@@ -14,6 +14,7 @@ patterns = ['permission denied',
             'need to be root',
             'need root',
             'only root can do that',
+            'You don\'t have access to the history DB.',
             'authentication is required']