diff --git a/docs/CONTRIBUTE b/docs/CONTRIBUTE
index ac4222b5d8431f43e163dfc61097e5106e676d49..6bd21d9c3a31c625431c4f6be1be0e29c15b4e0e 100644
--- a/docs/CONTRIBUTE
+++ b/docs/CONTRIBUTE
@@ -145,5 +145,15 @@ How To Make a Patch
 
      diff -ur curl-original-dir curl-modfied-sources-dir > my-fixes.diff
 
- GNU diff exists for virtually all platforms, including all kinds of unixes
- and Windows.
+ The GNU diff and GNU patch tools exist for virtually all platforms, including
+ all kinds of unixes and Windows:
+
+ For unix-like operating systems:
+
+        http://www.fsf.org/software/patch/patch.html
+        http://www.gnu.org/directory/diffutils.html
+
+ For Windows:
+
+        http://gnuwin32.sourceforge.net/packages/patch.htm
+        http://gnuwin32.sourceforge.net/packages/diffutils.htm