diff --git a/_pytest/python.py b/_pytest/python.py
index 8a3fcd51a..2ddf83ef9 100644
--- a/_pytest/python.py
+++ b/_pytest/python.py
@@ -1861,6 +1861,27 @@ class FixtureDef:
         return ("<FixtureDef name=%r scope=%r baseid=%r >" %
                 (self.argname, self.scope, self.baseid))
 
+def handle_mock_module_patching(function, startindex):
+    """
+    Special treatment when test_function is decorated
+    by mock.patch
+    """
+    for candidate_module_name in ('unittest.mock', 'mock'):
+        # stdlib comes first
+        try:
+            mock = sys.modules[candidate_module_name]
+        except KeyError:
+            pass
+        else:
+            for patching in getattr(function, "patchings", []):
+                if (not patching.attribute_name
+                        and patching.new is mock.DEFAULT):
+                    startindex += 1
+            break
+    else:
+        startindex += len(getattr(function, "patchings", []))
+    return startindex
+
 def getfuncargnames(function, startindex=None):
     # XXX merge with main.py's varnames
     #assert not inspect.isclass(function)
@@ -1870,13 +1891,7 @@ def getfuncargnames(function, startindex=None):
     if startindex is None:
         startindex = inspect.ismethod(function) and 1 or 0
     if realfunction != function:
-        mock = sys.modules.get('mock')
-        if mock is not None:
-            for patching in getattr(function, "patchings", []):
-                if not patching.attribute_name and patching.new is mock.DEFAULT:
-                    startindex += 1
-        else:
-            startindex += len(getattr(function, "patchings", []))
+        startindex = handle_mock_module_patching(function, startindex)
         function = realfunction
     argnames = inspect.getargs(py.code.getrawcode(function))[0]
     defaults = getattr(function, 'func_defaults',