diff --git a/Lib/string.py b/Lib/string.py
index 92158ee..e449c20 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -475,7 +475,7 @@
 	n = len(s)
 	if n >= width: return s
 	sign = ''
-	if s[0] in ('-', '+'):
+	if s[:1] in ('-', '+'):
 		sign, s = s[0], s[1:]
 	return sign + '0'*(width-n) + s