diff --git a/tests/rules/test_composer_not_command.py b/tests/rules/test_composer_not_command.py
index 518b97a5..4d0a9458 100644
--- a/tests/rules/test_composer_not_command.py
+++ b/tests/rules/test_composer_not_command.py
@@ -5,45 +5,87 @@ from thefuck.types import Command
 # tested with composer version 1.9.0
 
 # command: composer udpate
-case_single_command_with_one_suggestion = ("composer udpate", r'\n'
-                                           '                                                                  ''\n'
-                                           r'  [Symfony\Component\Console\Exception\CommandNotFoundException]  ''\n'
-                                           '  Command "udpate" is not defined.                                ''\n'
-                                           '                                                                  ''\n'
-                                           '  Did you mean this?                                              ''\n'
-                                           '      update                                                      ''\n'
-                                           '                                                                  ''\n'
-                                           '\n'
-                                           )
+case_single_command_with_one_suggestion = (
+    "composer udpate",
+    r"\n"
+    "                                                                  "
+    "\n"
+    r"  [Symfony\Component\Console\Exception\CommandNotFoundException]  "
+    "\n"
+    '  Command "udpate" is not defined.                                '
+    "\n"
+    "                                                                  "
+    "\n"
+    "  Did you mean this?                                              "
+    "\n"
+    "      update                                                      "
+    "\n"
+    "                                                                  "
+    "\n"
+    "\n",
+)
 case_single_command_with_one_suggestion_expected = "composer update"
 
 # command: composer selupdate
-case_single_command_with_many_suggestions = ("composer selupdate", r'\n'
-                                             '                                                                  ''\n'
-                                             r'  [Symfony\Component\Console\Exception\CommandNotFoundException]  ''\n'
-                                             '  Command "selupdate" is not defined.                             ''\n'
-                                             '                                                                  ''\n'
-                                             '  Did you mean one of these?                                      ''\n'
-                                             '      update                                                      ''\n'
-                                             '      self-update                                                 ''\n'
-                                             '      selfupdate                                                  ''\n'
-                                             '                                                                  ''\n'
-                                             '\n'
-                                             )
-case_single_command_with_many_suggesitons_expected = ["composer update", "composer self-update", "composer selfupdate"]
+case_single_command_with_many_suggestions = (
+    "composer selupdate",
+    r"\n"
+    "                                                                  "
+    "\n"
+    r"  [Symfony\Component\Console\Exception\CommandNotFoundException]  "
+    "\n"
+    '  Command "selupdate" is not defined.                             '
+    "\n"
+    "                                                                  "
+    "\n"
+    "  Did you mean one of these?                                      "
+    "\n"
+    "      update                                                      "
+    "\n"
+    "      self-update                                                 "
+    "\n"
+    "      selfupdate                                                  "
+    "\n"
+    "                                                                  "
+    "\n"
+    "\n",
+)
+case_single_command_with_many_suggesitons_expected = [
+    "composer update",
+    "composer self-update",
+    "composer selfupdate",
+]
 
 
-@pytest.mark.parametrize('command', [Command(*v) for v in [
-    case_single_command_with_one_suggestion,
-    case_single_command_with_many_suggestions
-]])
+@pytest.mark.parametrize(
+    "command",
+    [
+        Command(*v)
+        for v in [
+            case_single_command_with_one_suggestion,
+            case_single_command_with_many_suggestions,
+        ]
+    ],
+)
 def test_match(command):
     assert match(command)
 
 
-@pytest.mark.parametrize('command, new_command', [(Command(*t[0]), t[1]) for t in [
-    (case_single_command_with_one_suggestion, case_single_command_with_one_suggestion_expected),
-    (case_single_command_with_many_suggestions, case_single_command_with_many_suggesitons_expected)
-]])
+@pytest.mark.parametrize(
+    "command, new_command",
+    [
+        (Command(*t[0]), t[1])
+        for t in [
+            (
+                case_single_command_with_one_suggestion,
+                case_single_command_with_one_suggestion_expected,
+            ),
+            (
+                case_single_command_with_many_suggestions,
+                case_single_command_with_many_suggesitons_expected,
+            ),
+        ]
+    ],
+)
 def test_get_new_command(command, new_command):
     assert get_new_command(command) == new_command
diff --git a/tests/rules/test_composer_not_package.py b/tests/rules/test_composer_not_package.py
index 51a32c44..bf82bfc6 100644
--- a/tests/rules/test_composer_not_package.py
+++ b/tests/rules/test_composer_not_package.py
@@ -7,112 +7,196 @@ from thefuck.types import Command
 # command:
 # composer require laravel-nova-csv-import
 # the one that started it all
-case_original = ("composer require laravel-nova-csv-import", '\n'
-                 '                                                   ''\n'
-                 '  [InvalidArgumentException]                       ''\n'
-                 '  Could not find package laravel-nova-csv-import.  ''\n'
-                 '                                                   ''\n'
-                 '  Did you mean this?                               ''\n'
-                 '      simonhamp/laravel-nova-csv-import            ''\n'
-                 '                                                   ''\n'
-                 'require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...''\n'
-                 '\n')
+case_original = (
+    "composer require laravel-nova-csv-import",
+    "\n"
+    "                                                   "
+    "\n"
+    "  [InvalidArgumentException]                       "
+    "\n"
+    "  Could not find package laravel-nova-csv-import.  "
+    "\n"
+    "                                                   "
+    "\n"
+    "  Did you mean this?                               "
+    "\n"
+    "      simonhamp/laravel-nova-csv-import            "
+    "\n"
+    "                                                   "
+    "\n"
+    "require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]..."
+    "\n"
+    "\n",
+)
 case_original_expected = "composer require simonhamp/laravel-nova-csv-import"
 
 # command:
 # composer require datrack/elasticroute
-case_single_suggestion = ("composer require datrack/elasticroute", '\n'
-                          '                                                ''\n'
-                          '  [InvalidArgumentException]                    ''\n'
-                          '  Could not find package datrack/elasticroute.  ''\n'
-                          '                                                ''\n'
-                          '  Did you mean this?                            ''\n'
-                          '      detrack/elasticroute                      ''\n'
-                          '                                                ''\n'
-                          'require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...''\n'
-                          '\n')
+case_single_suggestion = (
+    "composer require datrack/elasticroute",
+    "\n"
+    "                                                "
+    "\n"
+    "  [InvalidArgumentException]                    "
+    "\n"
+    "  Could not find package datrack/elasticroute.  "
+    "\n"
+    "                                                "
+    "\n"
+    "  Did you mean this?                            "
+    "\n"
+    "      detrack/elasticroute                      "
+    "\n"
+    "                                                "
+    "\n"
+    "require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]..."
+    "\n"
+    "\n",
+)
 case_single_suggestion_expected = "composer require detrack/elasticroute"
 
 # command:
 # composer require potato
-case_many_suggestions = ("composer require potato", '\n'
-                         '                                  ''\n'
-                         '  [InvalidArgumentException]      ''\n'
-                         '  Could not find package potato.  ''\n'
-                         '                                  ''\n'
-                         '  Did you mean one of these?      ''\n'
-                         '      drteam/potato               ''\n'
-                         '      florence/potato             ''\n'
-                         '      kola/potato-orm             ''\n'
-                         '      jsyqw/potato-bot            ''\n'
-                         '      vundi/potato-orm            ''\n'
-                         '                                  ''\n\n'
-                         'require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...''\n'
-                         '\n')
-case_many_suggestions_expected = ["composer require drteam/potato",
-                                  "composer require florence/potato",
-                                  "composer require kola/potato-orm",
-                                  "composer require jsyqw/potato-bot",
-                                  "composer require vundi/potato-orm"]
+case_many_suggestions = (
+    "composer require potato",
+    "\n"
+    "                                  "
+    "\n"
+    "  [InvalidArgumentException]      "
+    "\n"
+    "  Could not find package potato.  "
+    "\n"
+    "                                  "
+    "\n"
+    "  Did you mean one of these?      "
+    "\n"
+    "      drteam/potato               "
+    "\n"
+    "      florence/potato             "
+    "\n"
+    "      kola/potato-orm             "
+    "\n"
+    "      jsyqw/potato-bot            "
+    "\n"
+    "      vundi/potato-orm            "
+    "\n"
+    "                                  "
+    "\n\n"
+    "require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]..."
+    "\n"
+    "\n",
+)
+case_many_suggestions_expected = [
+    "composer require drteam/potato",
+    "composer require florence/potato",
+    "composer require kola/potato-orm",
+    "composer require jsyqw/potato-bot",
+    "composer require vundi/potato-orm",
+]
 
 # command:
 # composer require datrack/elasticroute:*
-case_single_package_with_version_constraint = ("composer require datrack/elasticroute:*", '\n'
-                                               '                                                ''\n'
-                                               '  [InvalidArgumentException]                    ''\n'
-                                               '  Could not find package datrack/elasticroute.  ''\n'
-                                               '                                                ''\n'
-                                               '  Did you mean this?                            ''\n'
-                                               '      detrack/elasticroute                      ''\n'
-                                               '                                                ''\n\n'
-                                               'require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...''\n'
-                                               '\n')
-case_single_package_with_version_constraint_expected = "composer require detrack/elasticroute:*"
+case_single_package_with_version_constraint = (
+    "composer require datrack/elasticroute:*",
+    "\n"
+    "                                                "
+    "\n"
+    "  [InvalidArgumentException]                    "
+    "\n"
+    "  Could not find package datrack/elasticroute.  "
+    "\n"
+    "                                                "
+    "\n"
+    "  Did you mean this?                            "
+    "\n"
+    "      detrack/elasticroute                      "
+    "\n"
+    "                                                "
+    "\n\n"
+    "require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]..."
+    "\n"
+    "\n",
+)
+case_single_package_with_version_constraint_expected = (
+    "composer require detrack/elasticroute:*"
+)
 
 
 # command:
 # composer require potato:*
-case_single_package_with_version_constraint_many_suggestions = ("composer require potato:1.2.3", '\n'
-                                                                '                                  ''\n'
-                                                                '  [InvalidArgumentException]      ''\n'
-                                                                '  Could not find package potato.  ''\n'
-                                                                '                                  ''\n'
-                                                                '  Did you mean one of these?      ''\n'
-                                                                '      drteam/potato               ''\n'
-                                                                '      florence/potato             ''\n'
-                                                                '      kola/potato-orm             ''\n'
-                                                                '      jsyqw/potato-bot            ''\n'
-                                                                '      vundi/potato-orm            ''\n'
-                                                                '                                  ''\n\n'
-                                                                'require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]...''\n'
-
-                                                                '\n'
-                                                                )
-case_single_package_with_version_constraint_many_suggestions_expected = ["composer require drteam/potato:1.2.3",
-                                                                         "composer require florence/potato:1.2.3",
-                                                                         "composer require kola/potato-orm:1.2.3",
-                                                                         "composer require jsyqw/potato-bot:1.2.3",
-                                                                         "composer require vundi/potato-orm:1.2.3"]
+case_single_package_with_version_constraint_many_suggestions = (
+    "composer require potato:1.2.3",
+    "\n"
+    "                                  "
+    "\n"
+    "  [InvalidArgumentException]      "
+    "\n"
+    "  Could not find package potato.  "
+    "\n"
+    "                                  "
+    "\n"
+    "  Did you mean one of these?      "
+    "\n"
+    "      drteam/potato               "
+    "\n"
+    "      florence/potato             "
+    "\n"
+    "      kola/potato-orm             "
+    "\n"
+    "      jsyqw/potato-bot            "
+    "\n"
+    "      vundi/potato-orm            "
+    "\n"
+    "                                  "
+    "\n\n"
+    "require [--dev] [--prefer-source] [--prefer-dist] [--no-progress] [--no-suggest] [--no-update] [--no-scripts] [--update-no-dev] [--update-with-dependencies] [--update-with-all-dependencies] [--ignore-platform-reqs] [--prefer-stable] [--prefer-lowest] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--apcu-autoloader] [--] [<packages>]..."
+    "\n"
+    "\n",
+)
+case_single_package_with_version_constraint_many_suggestions_expected = [
+    "composer require drteam/potato:1.2.3",
+    "composer require florence/potato:1.2.3",
+    "composer require kola/potato-orm:1.2.3",
+    "composer require jsyqw/potato-bot:1.2.3",
+    "composer require vundi/potato-orm:1.2.3",
+]
 
 
-@pytest.mark.parametrize('command', [Command(*v) for v in [
-    case_original,
-    case_single_suggestion,
-    case_many_suggestions,
-    case_single_package_with_version_constraint,
-    case_single_package_with_version_constraint_many_suggestions
-]])
+@pytest.mark.parametrize(
+    "command",
+    [
+        Command(*v)
+        for v in [
+            case_original,
+            case_single_suggestion,
+            case_many_suggestions,
+            case_single_package_with_version_constraint,
+            case_single_package_with_version_constraint_many_suggestions,
+        ]
+    ],
+)
 def test_match(command):
     assert match(command)
 
 
-@pytest.mark.parametrize('command, new_command', [(Command(*t[0]), t[1]) for t in [
-    (case_original, case_original_expected),
-    (case_single_suggestion, case_single_suggestion_expected),
-    (case_many_suggestions, case_many_suggestions_expected),
-    (case_single_package_with_version_constraint, case_single_package_with_version_constraint_expected),
-    (case_single_package_with_version_constraint_many_suggestions,
-     case_single_package_with_version_constraint_many_suggestions_expected),
-]])
+@pytest.mark.parametrize(
+    "command, new_command",
+    [
+        (Command(*t[0]), t[1])
+        for t in [
+            (case_original, case_original_expected),
+            (case_single_suggestion, case_single_suggestion_expected),
+            (case_many_suggestions, case_many_suggestions_expected),
+            (
+                case_single_package_with_version_constraint,
+                case_single_package_with_version_constraint_expected,
+            ),
+            (
+                case_single_package_with_version_constraint_many_suggestions,
+                case_single_package_with_version_constraint_many_suggestions_expected,
+            ),
+        ]
+    ],
+)
 def test_get_new_command(command, new_command):
     assert get_new_command(command) == new_command
diff --git a/thefuck/rules/composer_not_command.py b/thefuck/rules/composer_not_command.py
index 6addd15f..bfdaeaef 100644
--- a/thefuck/rules/composer_not_command.py
+++ b/thefuck/rules/composer_not_command.py
@@ -1,37 +1,35 @@
 import re
-from thefuck.utils import replace_argument, for_app
+from thefuck.utils import for_app
 
 
-@for_app('composer')
+@for_app("composer")
 def match(command):
     # determine error type
     # matching "did you mean this" is not enough as composer also gives spelling suggestions for mistakes other than mispelled commands
-    is_undefined_command_error = r"[Symfony\Component\Console\Exception\CommandNotFoundException]" in command.output
-    suggestions_present = (('did you mean this?' in command.output.lower()
-                            or 'did you mean one of these?' in command.output.lower()))
+    is_undefined_command_error = "CommandNotFoundException" in command.output
+    suggestions_present = "Did you mean" in command.output
     return is_undefined_command_error and suggestions_present
 
 
 def get_new_command(command):
     # since the command class already tells us the original argument, we need not resort to regex
     broken_cmd = command.script_parts[1]
-    one_suggestion_only = 'did you mean this?' in command.output.lower()
+    one_suggestion_only = "Did you mean this?" in command.output
     if one_suggestion_only:
-        new_cmd = re.findall(r'Did you mean this\?[^\n]*\n\s*([^\n]*)', command.output)
-        return replace_argument(command.script, broken_cmd, new_cmd[0].strip())
-    else:
-        # there are multiple suggestions
-        # trim output text to make it more digestable by regex
-        trim_start_index = command.output.find("Did you mean one of these?")
-        short_output = command.output[trim_start_index:]
-        stripped_lines = [line.strip() for line in short_output.split("\n")]
-        # each of the suggested commands can be found from index 1 to the first occurence of blank string
-        try:
-            end_index = stripped_lines.index('')
-        except ValueError:
-            end_index = None
-        suggested_commands = stripped_lines[1:end_index]
-        return [
-            replace_argument(command.script, broken_cmd, cmd.strip())
-            for cmd in suggested_commands
-        ]
+        new_cmd = (
+            re.search(r"Did you mean this\?[^\n]*\n\s*([^\n]*)", command.output)
+            .group(1)
+            .strip()
+        )
+        return command.script.replace(broken_cmd, new_cmd)
+    # else there are multiple suggestions
+    # trim output text to make it more digestable by regex
+    trim_start_index = command.output.find("Did you mean")
+    short_output = command.output[trim_start_index:]
+    stripped_lines = [line.strip() for line in short_output.split("\n")]
+    # each of the suggested commands can be found from index 1 to the first occurrence of a blank string
+    end_index = stripped_lines.index("")
+    suggested_commands = stripped_lines[1:end_index]
+    return [
+        command.script.replace(broken_cmd, cmd.strip()) for cmd in suggested_commands
+    ]
diff --git a/thefuck/rules/composer_not_package.py b/thefuck/rules/composer_not_package.py
index 75f2bb68..89d757e2 100644
--- a/thefuck/rules/composer_not_package.py
+++ b/thefuck/rules/composer_not_package.py
@@ -1,42 +1,53 @@
 import re
-from thefuck.utils import replace_argument, for_app
+from thefuck.utils import for_app
 
 
-@for_app('composer')
+@for_app("composer")
 def match(command):
     # determine error type
     # matching "did you mean this" is not enough as composer also gives spelling suggestions for mistakes other than mispelled commands
     is_invalid_argument_exception = r"[InvalidArgumentException]" in command.output
-    is_unable_to_find_package = re.search(r"Could not find package (.*)\.", command.output) is not None
-    suggestions_present = (('did you mean this?' in command.output.lower()
-                            or 'did you mean one of these?' in command.output.lower()))
-    return is_invalid_argument_exception and is_unable_to_find_package and suggestions_present
+    is_unable_to_find_package = (
+        re.search(r"Could not find package (.*)\.", command.output) is not None
+    )
+    suggestions_present = "Did you mean" in command.output
+    return (
+        is_invalid_argument_exception
+        and is_unable_to_find_package
+        and suggestions_present
+    )
 
 
 def get_new_command(command):
     # because composer lets you install many packages at once, must look at output to determine the erroneous package name
-    wrong_package_name = re.search(r"Could not find package (.*)\.", command.output).group(1)
-    offending_script_param = wrong_package_name if (wrong_package_name in command.script_parts) else re.findall(
-        r"{}:[^ ]+".format(wrong_package_name), command.script)[0]
-    version_constraint = offending_script_param[len(wrong_package_name):]
-    one_suggestion_only = 'did you mean this?' in command.output.lower()
+    wrong_package_name = re.search(
+        r"Could not find package (.*)\.", command.output
+    ).group(1)
+    offending_script_param = (
+        wrong_package_name
+        if (wrong_package_name in command.script_parts)
+        else re.findall(r"{}:[^ ]+".format(wrong_package_name), command.script)[0]
+    )
+    version_constraint = offending_script_param[len(wrong_package_name) :]
+    one_suggestion_only = "Did you mean this?" in command.output
     if one_suggestion_only:
-        # wrong regex??
-        new_cmd = re.findall(r'Did you mean this\?[^\n]*\n\s*([^\n]*)', command.output)
-        return replace_argument(command.script, offending_script_param, new_cmd[0].strip() + version_constraint)
-    else:
-        # there are multiple suggestions
-        # trim output text to make it more digestable by regex
-        trim_start_index = command.output.find("Did you mean one of these?")
-        short_output = command.output[trim_start_index:]
-        stripped_lines = [line.strip() for line in short_output.split("\n")]
-        # each of the suggested commands can be found from index 1 to the first occurence of blank string
-        try:
-            end_index = stripped_lines.index('')
-        except ValueError:
-            end_index = None
-        suggested_commands = stripped_lines[1:end_index]
-        return [
-            replace_argument(command.script, offending_script_param, cmd + version_constraint)
-            for cmd in suggested_commands
-        ]
+        new_pkg = (
+            re.search(r"Did you mean this\?[^\n]*\n\s*([^\n]*)", command.output)
+            .group(1)
+            .strip()
+        )
+        return command.script.replace(
+            offending_script_param, new_pkg + version_constraint
+        )
+    # else there are multiple suggestions
+    # trim output text to make it more digestable by regex
+    trim_start_index = command.output.find("Did you mean")
+    short_output = command.output[trim_start_index:]
+    stripped_lines = [line.strip() for line in short_output.split("\n")]
+    # each of the suggested packages can be found from index 1 to the first occurrence of a blank string
+    end_index = stripped_lines.index("")
+    suggested_packages = stripped_lines[1:end_index]
+    return [
+        command.script.replace(offending_script_param, pkg + version_constraint)
+        for pkg in suggested_packages
+    ]