diff --git a/README.md b/README.md
index 2695e33..2a9def2 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,6 @@
 
 A diff viewer for markdown-formatted documents. 
 
-Uses the `wdiff` tool as a diffing engine. This produces an output that is more useful for copy-editing tasks. This wdiff comparison is then processed in a way that is aware of markdown formatting. The resulting output attempts to show differences of copy within the final document format (rather than differences of format).
+Uses the [`wdiff`](http://www.gnu.org/software/wdiff/) tool as a diffing engine. This produces an output that is more useful for copy-editing tasks. This wdiff comparison is then processed in a way that is aware of markdown formatting. The resulting output attempts to show differences of copy within the final document format (rather than differences of format).
 
 The markdown-sensitive processing of the wdiff comparison is at `server/components/wdiff/index.js`, for the curious.