diff --git a/pre_commit/languages/node.py b/pre_commit/languages/node.py
index a57c0a10..962ab2e6 100644
--- a/pre_commit/languages/node.py
+++ b/pre_commit/languages/node.py
@@ -23,7 +23,8 @@ def in_env(repo_cmd_runner, language_version):
     yield NodeEnv(repo_cmd_runner, language_version)
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     assert repo_cmd_runner.exists('package.json')
     directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
@@ -44,7 +45,7 @@ def install_environment(repo_cmd_runner, version='default',
             node_env.run("cd '{prefix}' && npm install -g")
             if additional_dependencies:
                 node_env.run("cd '{prefix}' && npm install -g " +
-                             (' ').join(additional_dependencies))
+                             ' '.join(additional_dependencies))
 
 
 def run_hook(repo_cmd_runner, hook, file_args):
diff --git a/pre_commit/languages/pcre.py b/pre_commit/languages/pcre.py
index 9d8fa410..4a7882c0 100644
--- a/pre_commit/languages/pcre.py
+++ b/pre_commit/languages/pcre.py
@@ -9,7 +9,8 @@ from pre_commit.util import shell_escape
 ENVIRONMENT_DIR = None
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     """Installation for pcre type is a noop."""
     raise AssertionError('Cannot install pcre repo.')
diff --git a/pre_commit/languages/python.py b/pre_commit/languages/python.py
index ebfba1b7..6da5e357 100644
--- a/pre_commit/languages/python.py
+++ b/pre_commit/languages/python.py
@@ -42,7 +42,8 @@ def norm_version(version):
     return version
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     assert repo_cmd_runner.exists('setup.py')
     directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
@@ -59,7 +60,7 @@ def install_environment(repo_cmd_runner, version='default',
         with in_env(repo_cmd_runner, version) as env:
             env.run("cd '{prefix}' && pip install .")
             if additional_dependencies:
-                env.run("cd '{prefix}' && pip install -U" +
+                env.run("cd '{prefix}' && pip install " +
                         (' ').join(additional_dependencies))
 
 
diff --git a/pre_commit/languages/ruby.py b/pre_commit/languages/ruby.py
index 55a18c69..8602daac 100644
--- a/pre_commit/languages/ruby.py
+++ b/pre_commit/languages/ruby.py
@@ -78,7 +78,8 @@ def _install_ruby(environment, version):
         environment.run('rbenv install {0}'.format(version))
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     directory = helpers.environment_dir(ENVIRONMENT_DIR, version)
     with clean_path_on_failure(repo_cmd_runner.path(directory)):
@@ -94,8 +95,8 @@ def install_environment(repo_cmd_runner, version='default',
             )
             if additional_dependencies:
                 ruby_env.run(
-                    'cd {prefix} && gem install --no-document ' + (' ').join(
-                        additional_dependencies)
+                    'cd {prefix} && gem install --no-document ' +
+                    ' '.join(additional_dependencies)
                 )
 
 
diff --git a/pre_commit/languages/script.py b/pre_commit/languages/script.py
index 5f6d97db..d6b25d05 100644
--- a/pre_commit/languages/script.py
+++ b/pre_commit/languages/script.py
@@ -6,7 +6,8 @@ from pre_commit.languages.helpers import file_args_to_stdin
 ENVIRONMENT_DIR = None
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     """Installation for script type is a noop."""
     raise AssertionError('Cannot install script repo.')
diff --git a/pre_commit/languages/system.py b/pre_commit/languages/system.py
index 1b49a8ce..eec64ad3 100644
--- a/pre_commit/languages/system.py
+++ b/pre_commit/languages/system.py
@@ -8,7 +8,8 @@ from pre_commit.languages.helpers import file_args_to_stdin
 ENVIRONMENT_DIR = None
 
 
-def install_environment(repo_cmd_runner, version='default',
+def install_environment(repo_cmd_runner,
+                        version='default',
                         additional_dependencies=None):
     """Installation for system type is a noop."""
     raise AssertionError('Cannot install system repo.')
diff --git a/pre_commit/repository.py b/pre_commit/repository.py
index e64b78e1..66374649 100644
--- a/pre_commit/repository.py
+++ b/pre_commit/repository.py
@@ -55,7 +55,7 @@ class Repository(object):
         dep_dict = defaultdict(lambda: defaultdict(set))
         for _, hook in self.hooks:
             dep_dict[hook['language']][hook['language_version']].update(
-                hook.get('dependencies', []))
+                hook.get('additional_dependencies', []))
         return dep_dict
 
     @cached_property