diff --git a/presubmit_support.py b/presubmit_support.py
index 0efaca1c8d..b2a94bc24b 100755
--- a/presubmit_support.py
+++ b/presubmit_support.py
@@ -216,6 +216,9 @@ class InputApi(object):
       # SCM (can happen in dual SCM configuration). (Slightly over aggressive)
       r"(|.*[\\\/])\.git[\\\/].*",
       r"(|.*[\\\/])\.svn[\\\/].*",
+      # There is no point in processing a patch file.
+      r".+\.diff$",
+      r".+\.patch$",
   )
 
   def __init__(self, change, presubmit_path, is_committing,
diff --git a/tests/presubmit_unittest.py b/tests/presubmit_unittest.py
index 8c25038231..c43bc4f8a2 100755
--- a/tests/presubmit_unittest.py
+++ b/tests/presubmit_unittest.py
@@ -1020,6 +1020,8 @@ class InputApiUnittest(PresubmitTestsBase):
           f('b.c/.git'),
           f('a/.git/bleh.py'),
           f('.git/bleh.py'),
+          f('bleh.diff'),
+          f('foo/bleh.patch'),
         ],
         [
           # Expected.
@@ -1031,7 +1033,7 @@ class InputApiUnittest(PresubmitTestsBase):
     self.mox.ReplayAll()
 
     self.assertEqual(len(input_api.DEFAULT_WHITE_LIST), 21)
-    self.assertEqual(len(input_api.DEFAULT_BLACK_LIST), 9)
+    self.assertEqual(len(input_api.DEFAULT_BLACK_LIST), 11)
     for item in files:
       results = filter(input_api.FilterSourceFile, item[0])
       for i in range(len(results)):