diff --git a/guessfilename/__init__.py b/guessfilename/__init__.py
index 84920e1..acc6f73 100755
--- a/guessfilename/__init__.py
+++ b/guessfilename/__init__.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
-PROG_VERSION = u"Time-stamp: <2018-04-22 19:15:01 vk>"
+PROG_VERSION = u"Time-stamp: <2018-05-05 16:36:09 vk>"
 
 
 # TODO:
@@ -131,6 +131,10 @@ class GuessFilename(object):
                                           '([012]\d)([012345]\d)(([012345]\d))?' + '(.*)?.(png|jpg)', re.UNICODE)
     ANDROID_SCREENSHOT_INDEXGROUPS = [1, '-', 2, '-', 3, 'T', 4, '.', 5, '.', 7, 8, ' -- screenshots android.', 9]
 
+    # Firefox_Screenshot_2018-05-03T20-07-14.972Z.png
+    EASY_SCREENSHOT_REGEX = re.compile('Firefox_Screenshot_(' + DAY_REGEX + ')T' + TIME_FUZZY_REGEX + '\.\d{3}Z(.*).png')
+    EASY_SCREENSHOT_INDEXGROUPS = [1, 'T', 2, '.', 3, '.', 5, ' Firefox - -- screenshots.png']
+
     TIMESTAMP_DELIMITERS = '[.;:-]?'
     DATESTAMP_REGEX = '([12]\d{3})' + TIMESTAMP_DELIMITERS + '([01]\d)' + TIMESTAMP_DELIMITERS + '([0123]\d)'
     TIMESTAMP_REGEX = '([012]\d)' + TIMESTAMP_DELIMITERS + '([012345]\d)(' + TIMESTAMP_DELIMITERS + '([012345]\d))?'
@@ -634,6 +638,12 @@ class GuessFilename(object):
         if datetimestr and self.contains_one_of(oldfilename, ["hipster", "Hipster"]):
             return datetimestr + ' Hipster-PDA vollgeschrieben -- scan notes.' + extension
 
+        # 2018-05-05: Files generated by "Easy Screenshot" (Firefox add-on)
+        # Firefox_Screenshot_2018-05-03T20-07-14.972Z.png
+        regex_match = re.match(self.EASY_SCREENSHOT_REGEX, oldfilename)
+        if regex_match:
+            return self.build_string_via_indexgroups(regex_match, self.EASY_SCREENSHOT_INDEXGROUPS)
+
         # 2017-12-02: Files from screenshots from xfce-tool "Screenshot"
         # example: Screenshot_2017-11-07_07-52-59 my description.png
         regex_match = re.match(self.SCREENSHOT1_REGEX, oldfilename)