Fixed typo in README.
diff --git a/README.md b/README.md
index b3387eb..63cecda 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 fixnum
 ======
 
-A fixed-width size integer library for Dart.
+A fixed-width 32- and 64- bit integer library for Dart.
 - - -
 The fixnum package provides data types for signed 32- and 64-bit integers.
 The integer implementations in this library are designed to work identically