Use repr() for bad input strings; this makes the empty string or binary characters more visible
diff --git a/Lib/fractions.py b/Lib/fractions.py
index 0d85f15..f06e4d4 100755
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -70,7 +70,7 @@
                 input = numerator
                 m = _RATIONAL_FORMAT.match(input)
                 if m is None:
-                    raise ValueError('Invalid literal for Fraction: ' + input)
+                    raise ValueError('Invalid literal for Fraction: %r' % input)
                 numerator = m.group('num')
                 decimal = m.group('decimal')
                 if decimal: