diff --git a/docs/mirrors.md b/docs/mirrors.md
index a431c4c0..ab276546 100644
--- a/docs/mirrors.md
+++ b/docs/mirrors.md
@@ -56,3 +56,13 @@ you want to use in addition to the postmarketOS binary package repository.
 pmbootstrap config mirrors.pmaports_custom http://custom-repository-here
 pmbootstrap config mirrors.systemd_custom http://custom-repository-here/extra-repos/systemd
 ```
+
+### Bootstrapping a repository for an additional architecture
+
+See also the [Environment Variables](environment_variables.md) section
+for a workaround when the APKINDEX is missing
+(e.g., if the repository for the additional architecture isn’t ready yet):
+
+```sh
+PMB_APK_FORCE_MISSING_REPOSITORIES=1 pmbootstrap install
+```