diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3702777..1166500 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -24,6 +24,18 @@ Tools team member.  Once you have obtained review, you may merge.
 Note that for the `c10s` branch, the pipeline is currently not green.
 On the `c8s` and `c9s` branches, it is green and should remain so.
 
+# Building locally
+
+It is recommend to use the `mock` tool to build in a clean build
+environment.  Use `centpkg srpm` to create the source RPM.
+
+If you want to build locally, be aware that the patch-git tooling
+picks up additional patches in the `$HOME/rpmbuild` directory
+hierarchy.  You can avoid this by building directly out of dist-git,
+without installing the source RPM using `rpm -i` first:
+
+    rpmbuild -bb -D "_sourcedir $PWD" glibc.spec
+
 # Trailers in Git commit messages
 
 The patch management tooling (in `patch-git.lua`) assumes that all Git