diff --git a/flake8/hooks.py b/flake8/hooks.py
index 7d493b8..a99bae3 100644
--- a/flake8/hooks.py
+++ b/flake8/hooks.py
@@ -35,8 +35,9 @@ def git_hook(complexity=-1, strict=False, ignore=None, lazy=False):
 
 def hg_hook(ui, repo, **kwargs):
     from flake8.main import check_file
-    _initpep8()
     complexity = ui.config('flake8', 'complexity', default=-1)
+    config = ui.config('flake8', 'config', default=True)
+    _initpep8(config_file=config)
     warnings = 0
 
     for file_ in _get_files(repo, **kwargs):
diff --git a/flake8/util.py b/flake8/util.py
index c8188ce..8d78edb 100644
--- a/flake8/util.py
+++ b/flake8/util.py
@@ -91,16 +91,17 @@ def skip_file(path, source=None):
     return _NOQA.search(content) is not None
 
 
-def _initpep8():
+def _initpep8(config_file=True):
     # default pep8 setup
     global pep8style
     import pep8
     if pep8style is None:
-        pep8style = pep8.StyleGuide(config_file=True)
+        pep8style = pep8.StyleGuide(config_file=config_file)
     pep8style.options.physical_checks = pep8.find_checks('physical_line')
     pep8style.options.logical_checks = pep8.find_checks('logical_line')
     pep8style.options.counters = dict.fromkeys(pep8.BENCHMARK_KEYS, 0)
     pep8style.options.messages = {}
-    pep8style.options.max_line_length = 79
+    if not pep8style.options.max_line_length:
+        pep8style.options.max_line_length = 79
     pep8style.args = []
     return pep8style