diff --git a/dvc/state.py b/dvc/state.py
index 836b59ec3..655d9dfd9 100644
--- a/dvc/state.py
+++ b/dvc/state.py
@@ -245,24 +245,19 @@ class State(object):
 
     @staticmethod
     def mtime_and_size(path):
-        size = 0
+        size = os.path.getsize(path)
         mtime = os.path.getmtime(path)
 
         if os.path.isdir(path):
             for root, dirs, files in os.walk(path):
-                for dname in dirs:
-                    p = os.path.join(root, dname)
-                    m = os.path.getmtime(p)
-                    if m > mtime:
-                        mtime = m
-
-                for fname in files:
-                    p = os.path.join(root, fname)
+                for name in dirs + files:
+                    p = os.path.join(root, name)
                     st = os.stat(p)
                     size += st.st_size
                     m = st.st_mtime
                     if m > mtime:
                         mtime = m
+
         # State of files handled by dvc is stored in db as TEXT.
         # We cast results to string for later comparisons with stored values.
         return str(int(nanotime.timestamp(mtime))), str(size)
diff --git a/tests/unit/state.py b/tests/unit/state.py
index b1608df10..18d6060a6 100644
--- a/tests/unit/state.py
+++ b/tests/unit/state.py
@@ -1,13 +1,23 @@
+import os
+
 from dvc.state import State
 from tests.basic_env import TestDvc
 
 
-class TestMtimeAndSizeReturnType(TestDvc):
+class TestMtimeAndSize(TestDvc):
     def test(self):
         file_time, file_size = State.mtime_and_size(self.DATA)
         dir_time, dir_size = State.mtime_and_size(self.DATA_DIR)
 
+        actual_file_size = os.path.getsize(self.DATA)
+        actual_dir_size = (os.path.getsize(self.DATA_DIR)
+                           + os.path.getsize(self.DATA)
+                           + os.path.getsize(self.DATA_SUB_DIR)
+                           + os.path.getsize(self.DATA_SUB))
+
         self.assertIs(type(file_time), str)
         self.assertIs(type(file_size), str)
+        self.assertEqual(file_size, str(actual_file_size))
         self.assertIs(type(dir_time), str)
         self.assertIs(type(dir_size), str)
+        self.assertEqual(dir_size, str(actual_dir_size))