THREADING: update cURL thread safety link
diff --git a/THREADING.md b/THREADING.md
index e9be8b9..77160a4 100644
--- a/THREADING.md
+++ b/THREADING.md
@@ -63,7 +63,7 @@ General Case
------------
By default we use libcurl, which has its own ![recommendations for
-thread safety](http://curl.haxx.se/libcurl/c/libcurl-tutorial.html#Multi-threading).
+thread safety](https://curl.haxx.se/libcurl/c/threadsafe.html).
If libcurl was not found or was disabled, libgit2 uses OpenSSL to be
able to use HTTPS as a transport. This library is made to be