diff --git a/flake.nix b/flake.nix
index 44000c9ab..bde792db3 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,6 +1,14 @@
 {
   description = "Tahoe-LAFS, free and open decentralized data store";
 
+  nixConfig = {
+    # Supply configuration for the build cache updated by our CI system.  This
+    # should allow most users to avoid having to build a large number of
+    # packages (otherwise necessary due to our Python package overrides).
+    substituters = ["https://tahoe-lafs-opensource.cachix.org"];
+    trusted-public-keys = ["tahoe-lafs-opensource.cachix.org-1:eIKCHOPJYceJ2gb74l6e0mayuSdXqiavxYeAio0LFGo="];
+  };
+
   inputs = {
     # A couple possible nixpkgs pins.  Ideally these could be selected easily
     # from the command line but there seems to be no syntax/support for that.