diff --git a/src/docs/user/installation_guide.diviner b/src/docs/user/installation_guide.diviner
--- a/src/docs/user/installation_guide.diviner
+++ b/src/docs/user/installation_guide.diviner
@@ -134,6 +134,13 @@
   somewhere/ $ git clone https://we.phorge.it/source/arcanist.git
   somewhere/ $ git clone https://we.phorge.it/source/phorge.git
 
+Then, to avoid errors in recent git versions, mark Arcanist and Phorge as safe
+at system level. This allows unprivileged users (like your webserver user) to run
+things like `git log` in these locations:
+
+  $ sudo git config --system --add safe.directory somewhere/arcanist
+  $ sudo git config --system --add safe.directory somewhere/phorge
+
 Next Steps
 ==========