diff --git a/pre_commit/git.py b/pre_commit/git.py
index ea065370..3802b5c0 100644
--- a/pre_commit/git.py
+++ b/pre_commit/git.py
@@ -1,14 +1,12 @@
+import functools
 import os
-import re
 import pkg_resources
+import re
 from plumbum import local
 
 from pre_commit.util import memoize_by_cwd
 
 
-def _get_root_original():
-    return local['git']['rev-parse', '--show-toplevel']().strip()
-
 def _get_root_new():
     path = os.getcwd()
     while len(path) > 1:
@@ -22,7 +20,6 @@ def _get_root_new():
 @memoize_by_cwd
 def get_root():
     return _get_root_new()
-    return local['git']['rev-parse', '--show-toplevel']().strip()
 
 
 @memoize_by_cwd
@@ -50,23 +47,24 @@ def get_staged_files():
     return local['git']['diff', '--staged', '--name-only']().splitlines()
 
 
-@memoize_by_cwd
-def get_staged_files_matching(expr):
-    regex = re.compile(expr)
-    return set(
-        filename for filename in get_staged_files() if regex.search(filename)
-    )
-
-
 @memoize_by_cwd
 def get_all_files():
     return local['git']['ls-files']().splitlines()
 
 
-# Smell: this is duplicated above
-@memoize_by_cwd
-def get_all_files_matching(expr):
-    regex = re.compile(expr)
-    return set(
-        filename for filename in get_all_files() if regex.search(filename)
-    )
\ No newline at end of file
+def get_files_matching(all_file_list_strategy):
+    @functools.wraps(all_file_list_strategy)
+    @memoize_by_cwd
+    def wrapper(expr):
+        regex = re.compile(expr)
+        return set(
+            filename
+            for filename in all_file_list_strategy()
+            if regex.search(filename)
+        )
+    return wrapper
+
+
+
+get_staged_files_matching = get_files_matching(get_staged_files)
+get_all_files_matching = get_files_matching(get_all_files)
diff --git a/pre_commit/util.py b/pre_commit/util.py
index 3a238590..648b7892 100644
--- a/pre_commit/util.py
+++ b/pre_commit/util.py
@@ -22,15 +22,16 @@ class cached_property(object):
 
 def memoize_by_cwd(func):
     """Memoize a function call based on os.getcwd()."""
-    cache = {}
     @functools.wraps(func)
     def wrapper(*args):
         cwd = os.getcwd()
         key = (cwd,) + args
         try:
-            return cache[key]
+            return wrapper._cache[key]
         except KeyError:
-            ret = cache[key] = func(*args)
+            ret = wrapper._cache[key] = func(*args)
             return ret
 
+    wrapper._cache = {}
+
     return wrapper