diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 0ea4a5811d7..9cf3e076211 100755
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -108,7 +108,7 @@ def _search_end(self):
 	# the 5 characters "From ".
 
 	_fromlinepattern = r"From \s*[^\s]+\s+\w\w\w\s+\w\w\w\s+\d?\d\s+" \
-			   r"\d?\d:\d\d:\d\d(\s+[^\s]+)?\s+\d\d\d\d\s*$"
+			   r"\d?\d:\d\d(:\d\d)?(\s+[^\s]+)?\s+\d\d\d\d\s*$"
 	_regexp = None
 
 	def _isrealfromline(self, line):