diff --git a/linebot/__about__.py b/linebot/__about__.py
index f94b51eec..317678690 100644
--- a/linebot/__about__.py
+++ b/linebot/__about__.py
@@ -16,7 +16,7 @@
 
 from __future__ import unicode_literals
 
-__version__ = '1.0.1'
+__version__ = '1.0.2'
 __author__ = 'LINE Corporation'
 __copyright__ = 'Copyright 2016, LINE Corporation'
 __license__ = 'Apache 2.0'
diff --git a/linebot/webhook.py b/linebot/webhook.py
index 0cbf746d0..2b5d46eba 100644
--- a/linebot/webhook.py
+++ b/linebot/webhook.py
@@ -37,7 +37,10 @@
 
 if hasattr(hmac, "compare_digest"):
     def compare_digest(val1, val2):
-        """compare_digest method.
+        """compare_digest function.
+
+        If hmac module has compare_digest function, use it.
+        Or not, use linebot.utils.safe_compare_digest.
 
         :param val1: string or bytes for compare
         :type val1: str | bytes
@@ -49,7 +52,10 @@ def compare_digest(val1, val2):
         return hmac.compare_digest(val1, val2)
 else:
     def compare_digest(val1, val2):
-        """compare_digest method.
+        """compare_digest function.
+
+        If hmac module has compare_digest function, use it.
+        Or not, use linebot.utils.safe_compare_digest.
 
         :param val1: string or bytes for compare
         :type val1: str | bytes