diff --git a/Lib/argparse.py b/Lib/argparse.py
index 83878b1..5e7b333 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1256,7 +1256,10 @@ class _ActionsContainer(object):
         self._defaults = {}
 
         # determines whether an "option" looks like a negative number
-        self._negative_number_matcher = _re.compile(r'^-\d+$|^-\d*\.\d+$')
+        _ngt_nmbr_pattern  = r'^-\d+$|^-\d*\.\d+$|^-\d+\.$|'
+        _ngt_nmbr_pattern += r'^-\d+\.?[eE][+-]?\d+$|'
+        _ngt_nmbr_pattern += r'^-\d*\.\d+[eE][+-]?\d+$'
+        self._negative_number_matcher = _re.compile(_ngt_nmbr_pattern)
 
         # whether or not there are any optionals that look like negative
         # numbers -- uses a list so it can be shared and edited